JP2023018084A - Laser beam method and system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide methods and apparatuses for manipulating and modulating of laser beams.

SOLUTION: Methods and apparatuses of the present disclosure enable activating and deactivating of laser beams, while laser systems maintain their operating power. Further, the present disclosure provides a hybrid pump module 2200 configured to be coupled to an optical fiber having a core and at least one clad. The hybrid pump module 2200 includes: at least one focusing lens disposed in an optical path of the optical fiber; a plurality of diode modules 2210 disposed in an optical path of the clad, each diode module being configured to output a multi-mode beam; and at least one core associated module which is disposed in an optical path of the core and configured to provide selected functions. Further, the present disclosure provides apparatus and methods configured for frequency doubling of optical radiation.

SELECTED DRAWING: Figure 10A

COPYRIGHT: (C)2023,JPO&INPIT

Description

The present invention relates to laser beam methods and systems.

The ability to manipulate beams emitted from lasers, laser beam arrays, and fiber optic arrays has applications in welding, cutting, surveying, the clothing industry, laser fusion, communications, laser printing, CD or optical disks, spectroscopy, heat treatment, barcodes. It is becoming important in various fields such as scanners, laser cooling, tracking technology and targeting technology. Laser applications in these and other related fields often require rapid activation (start of irradiation) and deactivation (stop of irradiation) of a laser beam.

Methods currently used to manipulate (activate/deactivate) fiber optic beams require manipulation of the output of the laser system. For example, "on"/"off" (shutdown) the seed beam device, transmit/block the seed beam, or turn off its current. These power manipulations are relatively slow (in the range of 1-5 KHz) due to, for example, the spontaneous emission time of fiber lasers, and when the laser emits an amplified spontaneous emission, one of the components of the laser system parts may be damaged.

There is a long-felt need for methods and/or apparatus that enable high-speed manipulation (activation/deactivation) of high-power laser beams, for example, for use during beam scanning or other high-speed material processing. .

High-power fiber lasers and fiber amplifiers require high-intensity pump sources to excite the ions to initiate the laser process, and efficient techniques for coupling with doped fibers. Coupling of the signal output to the fiber core is also important.

A common method of combining pump and/or signal light with a doped fiber is with a fused coupler, which is a fiber combiner or fused tapered fiber bundle (TFB) based on end-pumping technology. A TFB combiner with signal feedthrough includes a central input signal fiber and an output pigtail (curled) double-clad (DC) fiber to combine the signal and pump light into a single pigtail fiber. Uses of TFBs include guiding signal light and pump light surrounded by multiple multimode fibers. The fiber bundle is slowly melted and tapered to match the diameter of the fiber bundle to the diameter of the output pigtail fiber. After taper, the fiber bundle is cut around the taper waist and fusion spliced to the output pigtail DC fiber. However, fiber bundle taper is inherently accompanied by an increase in the numerical aperture (NA) of the pump light and a change in the mode field diameter (MFD) of the signal light. Therefore, the optical and mechanical alignment requirements required between the tapered fiber bundle and the output pigtail DC fiber, for example, can introduce some drawbacks to TFB structures.
Such drawbacks include, for example:
less flexibility in choosing the input fiber to match the output pigtail DC fiber after taper;
A slight mismatch or mismatch in the signal mode field diameter (MFD) between the tapered input signal fiber and the output pigtail DC fiber results in degraded beam quality, primarily related to signal insertion loss, that it can cause catastrophic damage to the fiber during high power operation;
In the case of counter-propagating signals, e.g. for counter-propagating pumped fiber amplifiers, signal insertion loss (up to 10%) damages the pump diodes due to their poor isolation to the amplified signal light. that there is a risk of giving
is mentioned.

Another common technique is by using a tapered capillary around the multiclad fiber or by directly fusing one or more tapered multimode fibers to the outermost cladding of the multiclad fiber. Monolithic all-fiber couplers, such as progressive transfer (GT) wave couplers.

However, the coupling efficiency of current combiners is not sufficient for use in very high power amplifiers and lasers. In addition, since the signal fiber is tapered along with the pump fiber, the core diameter of the signal fiber becomes small, which causes a significant mismatch in coupling with the double-clad fiber having a large mode-field diameter. occur. A mismatch with such a large mode field diameter causes unacceptably high signal loss, and can also cause temperature rise and damage to the TFB.

Another drawback is the susceptibility to parasitic nonlinear processes, primarily stimulated Brillouin scattering (SBS), which occurs when the linewidth of the laser signal is narrower than a few tens of megahertz. This is due to the long interaction length of the optical signal field with the core material of the fiber (due to the additional fiber length of the component).

Therefore, there is a need for a new technique that can overcome the above drawbacks, reduce the number of fusion splices, and reduce energy loss.

The present invention relates, in some embodiments, to frequency conversion of high average power laser beams in nonlinear crystals (NLCs). The present invention relates to means for correcting the deleterious phase mismatch (MP) between the originally occurring fundamental frequency input beam and the frequency converted output beam of a single or multiple NLC chains.

Previous attempts to achieve high average power harmonic conversion have reached limits determined by the damage threshold (damage in the bulk of the crystal or on its antireflection coating) or absorption-induced thermal effects.

With improvements in crystals and their antireflection (AR) coatings, thermally induced phase mismatch (TMP) has become a major limiting factor for high average power performance. One option for controlling TMP is to use ultra-low absorption crystals. One example is lithium triborate (LBO) for frequency doubling of 1064 nm lasers.

However, at a given power level, heating of the crystal will start to degrade performance, so some compensation method must be used.

One approach reported in the literature is to use two crystals with intermediate phase mismatch compensators (PMCs). PMCs are optical elements that exhibit chromatic dispersion and/or polarization dependent refractive index. This dispersion can be a material-specific property ([D. Fluck, and P. Gunter, "Efficient second-harmonic generation by lens wave-guiding in KNbO crystals", Optics Comm. 147, 305-308 (1998); A. K. Hansen, M. Tawfieq, O. B. Jensen, P. E. Andersen, B. Sumpf, G. Erbert, and P. M. Petersen, "Concept for power scaling second harmonic generation using a cascade of nonlinear crystals" Optics Express 23, 15921-15934 (2015) A. K. Hansen, O. B. Jensen, B. Sumpf, G. Erbert, A. Unterhuber, W. Drexler, P. E. Andersen, P. M. l Petersen, "Generation of 3.5 W of diffraction-limited green light from SHG of a single tapered diode laser in a cascade of nonlinear crystals" Proc. of SPIE Vol. 8964 (2016); X. Liu, X. Shen, J. Yin, and X. Li, "Three-crystal method for thermally induced phase mismatch compensation in second-harmonic generation" , J. Opt. Soc. Am. B 34, 383-388 (2017)]). Alternatively, this dispersion can be imposed by an external field (e.g., an electric field applied to an electro-optic material such as a Pockels cell) [Z. Cui, D. Liu, 1, M. Sun, J. Miao, and J. Zhu, "Compensation method for temperature-induced phase mismatch during frequency conversion in high-power laser systems" JOSA B 33, 525-534 (2016)].).

Experiments and simulations have shown that PMC is very effective in compensating the MP of the second crystal of a two crystal frequency multiplication chain. However, at sufficiently high input power, the MP of the first frequency conversion crystal needs to be better addressed.

A frequency doubling module used to convert the wavelength of the input laser light may consist of one or more nonlinear crystals (NLCs) arranged in series. Input light is focused on the first crystal and then relay-imaging with achromatic optics between subsequent crystals to maximize the multiplication per crystal and per multiplication system. The crystals are separated by a phase mismatch compensator (PMC), which has the function of correcting the phase mismatch between the fundamental and harmonic beams that occur during the doubling process, in front of the high-intensity interaction region of a particular crystal. You may

Generally, such systems are considered static systems even though some degree of control is attempted by varying the operating temperature of the crystal. Current frequency multiplying systems are configured to operate at a single operating point by adjusting the PMC to maintain a fixed amount of phase difference. Therefore, there is a need for active PMCs to provide enhanced capabilities.

In some embodiments of the invention,
by a laser system comprising at least one seed laser device and a coherent beam combining (CBC) system configured to receive a seed beam of said seed laser device and selectively provide an amplified laser beam; A method for conditioning a laser beam comprising:
The coherent beam combining (CBC) system comprising:
a plurality of phase adjusters, each arranged to enable constructive or destructive beam interference at the CBC point, a seed beam, a plurality of optical amplifiers, at least one beam splitter, and optionally the plurality of phase adjusters configured to be optically connected to at least one beam combiner;
at least one control circuit configured to monitor the beam interference at the CBC point and control at least one of the plurality of phase adjusters accordingly;
The method is
providing the laser beam by controlling the phase adjuster to activate the laser beam to provide constructive beam interference at the CBC point;
and ceasing provision of the laser beam by deactivating the laser beam by controlling the phase adjuster to provide destructive beam interference at the CBC point. provided.

In some embodiments, said step of controlling said phase adjuster to provide said constructive beam interference and activating said laser beam comprises: adjusting the phase adjuster to .

In some embodiments, the step of controlling the phase adjusters to provide the destructive interference and deactivating the laser beam comprises controlling half of the adjusted phase adjusters. to add a half phase (π) to the laser beam.

In some embodiments, the step of deactivating the laser beam by controlling the phase adjusters to provide the destructive interference comprises: controlling some of the adjusted phase adjusters to including adjusting.

In some embodiments, each of said phase adjusters is adjusted individually.

In some embodiments, the method further comprises adjusting the laser beam by adjusting some of the phase adjusters adjusted to provide the laser beam at maximum intensity. and adjusting the phase adjuster includes bringing the intensity of the laser beam to an intensity equal to a predetermined percentage of the maximum intensity.

In some embodiments, said step of deactivating said laser beam by controlling said phase adjuster to provide said destructive beam interference provides said destructive beam interference at a minimum intensity. adjusting the phase adjuster such that

In some embodiments of the invention,
A method for modulating a laser beam provided by a laser system comprising:
The laser system is
at least one seed laser device;
a fast optical modulator (FOM) configured to receive the seed beam of the seed laser device and adjust its bandwidth;
a coherent beam combining (CBC) system configured to receive the bandwidth-adjusted seed beam and provide an amplified laser beam;
The method is
said fast optical modulator ( activating said laser beam by controlling a FOM), thereby providing said laser beam;
controlling the fast optical modulator (FOM) to provide the seed beam with a second bandwidth (Δω2; Δω2>Δω1) set to disable constructive interference at the CBC point; and deactivating the laser beam by doing so, thereby stopping providing the laser beam.

In some embodiments,
The coherent beam combining (CBC) system comprises:
a plurality of phase adjusters, each arranged to enable constructive beam interference at a CBC point, said adjusted seed beam, a plurality of optical amplifiers, at least one beam splitter, and optionally the plurality of phase adjusters configured to be optically connected to at least one beam combiner of
at least one control circuit configured to monitor the beam interference at the CBC point and control at least one of the plurality of phase adjusters accordingly;
The step of activating the laser beam further includes controlling the phase adjuster to provide the constructive beam interference.

In some embodiments, said step of controlling said phase adjuster to provide said constructive beam interference adjusts said phase adjuster to provide said constructive beam interference at maximum intensity. Including steps.

In some embodiments of the invention,
A method for modulating a laser beam provided by a laser system comprising:
The laser system is
a coherent beam combining (CBC) system configured to receive a seed laser beam and provide an amplified laser beam;
a first seed laser device configured to provide a first seed beam having a first wavelength (λ1);
a second seed laser device configured to provide a second seed beam having a second wavelength (λ2; λ2≠λ1) different from the first wavelength;
an optical switch configured to link only one of the first seed beam and the second seed beam to the coherent beam combining (CBC) system;
The coherent beam combining (CBC) system comprises:
a linked seed beam, a plurality of optical amplifiers, at least one beam splitter, and a plurality of phase adjusters, each arranged to enable constructive or destructive beam interference at a CBC point; the plurality of phase adjusters configured to be optically connected to an optional at least one beam combiner;
at least one control circuit configured to monitor the beam interference at the CBC point and control at least one of the plurality of phase adjusters accordingly;
The method is
controlling the optical switch to link the first seed beam to the coherent beam combining (CBC) system to activate the laser beam and controlling the phase adjuster to enable constructive beam interference; and thereby providing said laser beam;
controlling the optical switch to link the second seed beam to the coherent beam combining (CBC) system to deactivate the laser beam to disable the constructive beam interference, thereby and c. ceasing to provide the beam.

In some embodiments, said step of controlling said phase adjuster to provide said constructive beam interference adjusts said phase adjuster to provide said constructive beam interference at maximum intensity. Including steps.

In some embodiments of the invention,
A method for modulating a laser beam provided by a laser system comprising:
The laser system is
a coherent beam combining (CBC) system configured to receive a seed laser beam and provide an amplified laser beam;
a first seed laser apparatus configured to provide a first seed beam having a first bandwidth (Δω1);
a second seed laser apparatus configured to provide a second seed beam having a second bandwidth (Δω2; Δω2>Δω1) wider than the first bandwidth;
an optical switch configured to link only one of the first seed beam and the second seed beam to the coherent beam combining (CBC) system;
the first bandwidth (Δω1) is set to enable the constructive beam interference at a CBC point of the coherent beam combining (CBC) system;
the second bandwidth (Δω2) is set to disable the constructive beam interference at the CBC point;
The method is
controlling the optical switch to link the first seed beam to the coherent beam combining (CBC) system to activate the laser beam to enable the constructive beam interference, thereby providing a step;
controlling the optical switch to link the second seed beam to the CBC system and deactivate the laser beam to disable the constructive beam interference, thereby stopping the provision of the laser beam; A method is provided, comprising:

In some embodiments,
The coherent beam combining (CBC) system comprises:
a plurality of phase adjusters, each arranged to enable constructive or destructive beam interference at said CBC point, linked seed beams, a plurality of optical amplifiers, at least one beam splitter; and the plurality of phase adjusters configured to be optically connected to and optionally at least one beam combiner;
at least one control circuit configured to monitor the beam interference at the CBC point and control at least one of the plurality of phase adjusters accordingly;
The step of activating the laser beam further includes controlling the phase adjuster to provide the constructive beam interference.

In some embodiments, said step of controlling said phase adjuster to provide said constructive beam interference adjusts said phase adjuster to provide said constructive beam interference at maximum intensity. Including steps.

In some embodiments of the invention,
A method for modulating a laser beam provided by a laser system comprising:
The laser system is
a coherent beam combining (CBC) system configured to receive a seed laser beam and provide an amplified laser beam;
a first seed laser device configured to provide a first seed beam having a first wavelength (λ1);
a second seed laser device configured to provide a second seed beam having a second wavelength (λ2; λ2≠λ1) different from the first wavelength;
an optical switch configured to link only one of the first seed beam and the second seed beam to the coherent beam combining (CBC) system;
receive the amplified laser beam, transmit the beam having the first wavelength (λ1) to the output of the laser system, and reflect the beam having the second wavelength (λ2), thereby providing an output laser beam a dichroic mirror configured to selectively provide the beam;
The method is
controlling the optical switch to link the first seed beam to the coherent beam combining (CBC) system to activate the laser beam, thereby transmitting the laser beam to provide the laser beam; a step;
controlling the optical switch to link the second seed beam to the coherent beam combining (CBC) system to deactivate the laser beam, thereby reflecting the laser beam to provide the laser beam; and c.

In some embodiments,
The coherent beam combining (CBC) system comprises:
a linked seed beam, a plurality of optical amplifiers, at least one beam splitter, and a plurality of phase adjusters, each arranged to enable constructive or destructive beam interference at a CBC point; the plurality of phase adjusters configured to be optically connected to an optional at least one beam combiner;
at least one control circuit configured to monitor the beam interference at the CBC point and control at least one of the plurality of phase adjusters accordingly;
The step of activating the laser beam further includes controlling the phase adjuster to provide the constructive beam interference.

In some embodiments, said step of controlling said phase adjuster to provide said constructive beam interference adjusts said phase adjuster to provide said constructive beam interference at maximum intensity. Including steps.

In some embodiments of the invention,
A method for modulating a laser beam provided by a laser system comprising:
The laser system is
a master oscillator power amplifier (MOPA) configured to receive a seed laser beam and provide an amplified laser beam;
a first seed laser device configured to provide a first seed beam having a first wavelength (λ1);
a second seed laser device configured to provide a second seed beam having a second wavelength (λ2; λ2≠λ1) different from said first wavelength;
an optical switch configured to link only one of the first seed beam and the second seed beam to the master oscillator power amplifier (MOPA);
receive the amplified laser beam, transmit the beam having the first wavelength (λ1) to the output of the laser system, and reflect the beam having the second wavelength (λ2), thereby providing an output laser a dichroic mirror configured to selectively provide the beam;
The method is
controlling the optical switch to link the first seed beam to the master oscillator power amplifier (MOPA) to activate the laser beam, thereby transmitting the laser beam to provide the laser beam; a step;
controlling the optical switch to link the second seed beam to a coherent beam combining (CBC) system to deactivate the laser beam, thereby reflecting the laser beam and providing the laser beam; and c. stopping.

In some embodiments of the invention,
A method for modulating a laser beam provided by a laser system comprising:
The laser system is
at least one seed laser device;
at least one optical polarization combiner (OPC) configured to receive a seed beam of said seed laser device and adjust its polarization direction, said polarization direction adjustment comprising at least two polarization components in said seed beam; the optical polarization combiner (OPC), wherein one of the polarization components has a predetermined polarization direction (P1), and
a coherent beam combining (CBC) system configured to receive the polarization adjusted seed beam and provide an amplified laser beam;
receiving the amplified laser beam, transmitting only the beam component having the predetermined polarization direction (P1) to the output of the laser system and reflecting the beam component having the other polarization direction, thereby causing the laser beam to a polarizing beam splitter (PBS) configured to selectively provide
The method is
activating said laser beam by controlling said optical polarization combiner (OPC) to provide a beam component having said predetermined polarization direction (P1) at an intensity (I1) greater than 50% of the total intensity of the beam; transforming, thereby providing said laser beam;
said laser beam by controlling said optical polarization combiner (OPC) to provide a beam component having said predetermined polarization direction (P1) at an intensity (I1) less than or equal to 50% of the total intensity of said laser beam; and c. deactivating, thereby stopping providing said laser beam.

In some embodiments, the method comprises controlling the optical polarization combiner (OPC) to produce the predetermined polarization direction (P1) with an intensity (I1) equal to a predetermined percentage of the total intensity of the seed laser beam. further comprising conditioning the laser beam by providing a beam component having a .

In some embodiments,
The coherent beam combining (CBC) system comprises:
a plurality of phase adjusters, said polarization adjusted seed beam, a plurality of optical amplifiers, at least one beam splitter each arranged to enable constructive or destructive beam interference at a CBC point; , and optionally the plurality of phase adjusters configured to be optically connected to at least one beam combiner;
at least one control circuit configured to monitor the beam interference at the CBC point and control at least one of the plurality of phase adjusters accordingly;
The method is
Further comprising controlling the phase adjuster to provide the constructive beam interference at the CBC point at least during the step of activating the laser beam.

In some embodiments,
The optical polarization combiner (OPC) is
A beam splitting assembly for receiving an input beam having a first polarization direction (P1) and a first output beam (B1(I1 , P1)) and a second output beam (B2(I2, P1)) having said first polarization direction (P1) and a second intensity (I2), said first the beam splitting assembly, wherein the sum of the intensity of and the second intensity (I1+I2) is equal to the intensity of the input beam;
a polarization converter configured to receive one of the first output beam and the second output beam (B1 or B2) output from the beam splitting assembly and convert the polarization thereof;
a polarizing beam splitter (PBS) for receiving the first output beam (B1(I1,P1)) and the polarization converted second output beam (B2(I2,P2)) and dividing them into the polarizing beam splitter (PBS) or coupler configured to combine to produce a third beam, polarization converted with the first output beam (B1(I1,P1)); receiving the second output beam (B2(I2, P2)) and combining them and then splitting them into two output beams, only one of the two split output beams being subjected to the coherent beam combining (CBC) ) the coupler configured to provide as an input to the system.

In some embodiments,
The beam splitting assembly comprises:
a beam splitter configured to receive an input beam and split the input beam into two beams;
a phase adjuster configured to adjust the phase of one of the two beams;
By receiving the two beams and providing their interference at two interference locations, the first output beam (B1(I1,P1)) and the second output beam (B2(I2,P1) ) and a coupler configured to provide
an electronic controller for monitoring one of said two interference locations and controlling said phase adjuster accordingly to enable constructive or destructive beam interference at the monitored interference location; and the electronic controller configured to provide destructive or constructive beam interference at unmonitored interference locations;
The step of controlling the optical polarization combiner (OPC) includes controlling the phase adjuster.

In some embodiments of the invention,
A method for modulating a laser beam provided by a laser system comprising:
The laser system is
at least one seed laser device;
at least one optical polarization combiner (OPC) configured to receive a seed beam of said seed laser device and adjust its polarization direction, said polarization direction adjustment comprising at least two polarization components in said seed beam; the optical polarization combiner (OPC), wherein one of the polarization components has a predetermined polarization direction (P1), and
a master oscillator power amplifier (MOPA) configured to receive the polarization adjusted seed beam and provide an amplified laser beam;
receiving the amplified laser beam, transmitting only the beam component having the predetermined polarization direction (P1) to the output of the laser system and reflecting the beam component having the other polarization direction, thereby causing the laser beam to a polarizing beam splitter (PBS) configured to selectively provide
The method is
activating said laser beam by controlling said optical polarization combiner (OPC) to provide a beam component having said predetermined polarization direction (P1) at an intensity (I1) greater than 50% of the total intensity of the beam; transforming, thereby providing said laser beam;
said laser beam by controlling said optical polarization combiner (OPC) to provide a beam component having said predetermined polarization direction (P1) at an intensity (I1) less than or equal to 50% of the total intensity of said laser beam; and c. deactivating, thereby stopping providing said laser beam.

In some embodiments of the invention,
A laser system configured to condition a laser beam, comprising:
at least one seed laser device;
at least one optical polarization combiner (OPC) configured to receive a seed beam of said seed laser device and adjust its polarization direction, said polarization direction adjustment comprising at least two polarization components in said seed beam; the optical polarization combiner (OPC), wherein one of the polarization components has a predetermined polarization direction (P1), and
a coherent beam combining (CBC) system configured to receive the polarization adjusted seed beam and provide an amplified laser beam;
receiving the amplified laser beam, transmitting only the beam component having the predetermined polarization direction (P1) to the output of the laser system and reflecting the beam component having the other polarization direction, thereby causing the laser beam to a polarizing beam splitter (PBS) configured to selectively provide a
An electronic control device,
activating said laser beam by controlling said optical polarization combiner (OPC) to provide a beam component having said predetermined polarization direction (P1) at an intensity (I1) greater than 50% of the total intensity of the beam; transforming, thereby providing said laser beam,
said laser beam by controlling said optical polarization combiner (OPC) to provide a beam component having said predetermined polarization direction (P1) at an intensity (I1) less than or equal to 50% of the total intensity of said laser beam; the electronic controller configured to deactivate, thereby stopping providing the laser beam;
A system is provided comprising:

In some embodiments,
The coherent beam combining (CBC) system comprises:
a plurality of phase adjusters, said polarization adjusted seed beam, a plurality of optical amplifiers, at least one beam splitter each arranged to enable constructive or destructive beam interference at a CBC point; , and optionally the plurality of phase adjusters configured to be optically connected to at least one beam combiner;
at least one control circuit configured to monitor the beam interference at the CBC point and control at least one of the plurality of phase adjusters accordingly.

In some embodiments,
The optical polarization combiner (OPC) is
A beam splitting assembly for receiving an input beam having a first polarization direction (P1) and a first output beam (B1(I1 , P1)) and a second output beam (B2(I2, P1)) having said first polarization direction (P1) and a second intensity (I2), said first the beam splitting assembly, wherein the sum of the intensity of and the second intensity (I1+I2) is equal to the intensity of the input beam;
a polarization converter configured to receive one of the first output beam and the second output beam (B1 or B2) output from the beam splitting assembly and convert the polarization thereof;
a polarizing beam splitter (PBS) for receiving the first output beam (B1(I1,P1)) and the polarization converted second output beam (B2(I2,P2)) and dividing them into the polarizing beam splitter (PBS) configured to combine to produce a third beam; or the first output beam (B1(I1,P1)) and the second polarization converted output beams (B2(I2, P2)) and splitting them into two output beams after combining them, and providing only one of said two output beams as an input to said coherent beam combining (CBC) system. and the coupler configured to:

In some embodiments,
The beam splitting assembly comprises:
a beam splitter configured to receive an input beam and split the input beam into two beams;
a phase adjuster configured to adjust the phase of one of the two beams;
By receiving the two beams and providing their interference at two interference locations, the first output beam (B1(I1,P1)) and the second output beam (B2(I2,P1) ) and a coupler configured to provide
an electronic controller for monitoring one of said two interference locations and controlling said phase adjuster accordingly to enable constructive or destructive beam interference at the monitored interference location; and the electronic controller configured to provide destructive or constructive beam interference at unmonitored interference locations.

In some embodiments of the invention,
A hybrid pump module configured to couple to an optical fiber having a core and at least one cladding, comprising:
at least one focusing lens positioned in the optical path of the optical fiber;
a plurality of diode modules disposed in the optical path of the cladding, each configured to output a multimode beam;
at least one core-associated module positioned in the optical path of the core,
(a) the ability to output a single-mode beam towards the core;
(b) receiving a beam from said core and coupling the received beam to an output optical fiber;
(c) the ability to receive a beam from said core and reflect the received beam back to said core; and
(d) receiving a beam from said core, reflecting a portion of the received beam back to said core, and coupling another portion of the received beam into an output optical fiber. A hybrid pump module is provided comprising: the core-associated module configured to provide:

In some embodiments, the hybrid pump module further comprises a volume Bragg grating (VBG) configured to narrowly lock the wavelength of the beam to a predetermined wavelength range.

In some embodiments, the plurality of diode modules and the core-associated modules are arranged in at least one row such that their output beams are parallel to each other row by row.

In some embodiments,
The plurality of diode modules and the core-related modules are arranged in two or more rows,
The hybrid pump module is
at least one polarizer beam combiner positioned in the optical path of the first beam train;
one or more folding mirrors for each additional beam column, each configured to reflect and redirect a corresponding column of parallel beams toward the polarizer beam combiner; and a mirror.

In some embodiments,
Each of the diode modules includes:
a broad area laser (BAL);
a folding mirror associated with the broadband laser (BAL), the folding mirror configured to have an optical path between the associated broadband laser (BAL) and the cladding;
optionally, at least one lens disposed between said broadband laser (BAL) and said associated folding mirror and configured to adjust the beam shape of said broadband laser (BAL); include.

In some embodiments,
the core related modules include seed related modules;
The seed-related module includes:
at least one seed input configured to couple to a seed laser device;
a folding mirror associated with the seed input in the optical path between the seed input and the core;
optionally, at least one lens disposed between said seed input and said associated folding mirror and configured to adjust the shape of the seed beam.

In some embodiments,
The seed-related module includes:
a beam amplifier configured to amplify the seed beam;
a tap or partial mirror configured to sample the seed beam, and a monitor configured to monitor and alert beam backward transmission;
and an isolator configured to allow transmission of light in only one direction.

In some embodiments,
the core-related module includes an output module;
The output module is
an output fiber, optionally including an end cap element;
a folding mirror associated with the output fiber in the optical path between the core and the output fiber;
optionally, at least one lens disposed between said output fiber and said associated folding mirror and configured to adjust the shape of the received core beam;
Optimally, including a pump dump.

In some embodiments,
the core-related module includes a high reflectance (HR) module;
The high reflectance (HR) module comprises:
a high reflectance (HR) mirror; and
a folding mirror associated with the high reflectance (HR) mirror in the optical path between the core and the high reflectance (HR) mirror;
optionally, at least one lens disposed between said high reflectivity (HR) mirror and said associated folding mirror and configured to adjust the shape of its associated beam.

In some embodiments, the high reflectance (HR) mirror is positioned between the high reflectance (HR) mirror and the associated fold mirror, and an intracavity adjustment configured to adjust the reflected beam. Further includes a vessel.

In some embodiments,
the core-related module includes a partial reflection (PR) module;
The partial reflection (PR) module comprises:
an output fiber, optionally including an end cap;
a partially reflective (PR) mirror positioned in the optical path of the output fiber;
a folding mirror associated with the partially reflective (PR) mirror in an optical path between the core and the partially reflective (PR) mirror;
optionally, at least one lens disposed between said partially reflective (PR) mirror and said associated folding mirror and configured to adjust the shape of its associated beam.

In some embodiments, the hybrid pump module further comprises at least one heat distribution element selected from the group consisting of base surfaces, ribs, threads, and any combination thereof.

In some embodiments of the invention,
A fiber amplification system,
an optical fiber comprising a core and at least one cladding;
and a hybrid pump module according to any of the above embodiments coupled to the first end of the optical fiber.

In some embodiments, the fiber amplification system further comprises at least one of pump dump and endcap elements.

In some embodiments, the fiber amplification system further comprises a hybrid pump module according to any of the embodiments above coupled to the second end of the optical fiber.

In some embodiments of the invention,
A fiber laser system,
an optical fiber comprising a core and at least one cladding;
A hybrid pump module according to any of the preceding embodiments coupled to the first end of the optical fiber; and
A system is provided comprising a fiber Bragg grating (FBG) or a hybrid pump module according to any of the above embodiments coupled to the second end of the optical fiber.

In some embodiments, the fiber laser system further comprises at least one of a pump dump and an endcap element.

Some embodiments of the present invention are based on adding a weak second harmonic seed beam to the high power fundamental beam before a nonlinear crystal output frequency multiplier (PFD-NLC). Therefore, the phase difference between the seed beam and the fundamental beam is controlled to obtain a conjugate phase difference to the phase difference occurring in the first PFD-NLC. This resulted in a minimum phase mismatch (MP) from the input of the PFD through the harmonic conversion region of the NLC.

In some embodiments, the temperature and/or angle is configured for optimal harmonic conversion in the maximum conversion zone (focal waist if using a lens, full length of the crystal if the beam is collimated). A modulated PFD-NLC is provided. Therefore, adding a seed beam provides sufficient parameters to reach within 5% of the conversion efficiency achieved in the absence of MP.

In some embodiments of the invention,
An apparatus configured to frequency double optical radiation, comprising:
at least two consecutive nonlinear crystals (NLCs) including a first nonlinear crystal and at least one second nonlinear crystal;
The first nonlinear crystal receives a fundamental beam at a fundamental frequency (FF) and emits a weak second harmonic beam at a second harmonic frequency (FH) together with a strong residual beam at the fundamental frequency (FF). wherein the power ratio between the weak second harmonic beam and the fundamental beam is less than 5×10 ⁻³ to 1;
The at least one second nonlinear crystal comprises the remnant beam at the fundamental frequency (FF) and the second harmonic beam at the second harmonic frequency (FH) from the previous nonlinear crystal (NLC). and output a strong frequency-doubled beam at said second harmonic frequency (FH) together with said remnant beam at said fundamental frequency (FF); A device is provided in which the power ratio is greater than 0.3:1.

In some embodiments, the apparatus generates the remnant beam at the fundamental frequency (FF) and the second harmonic beam at the second harmonic frequency (FH) before being received by the second nonlinear crystal. further comprising at least one phase mismatch compensator (PMC) configured to correct the phase relationship with .

In some embodiments, the apparatus samples the frequency-doubled intense beam and adjusts the phase mismatch compensator (PMC) accordingly to enable maximizing the power of the frequency-doubled beam. ), further comprising at least one feedback and control system configured to adjust .

In some embodiments,
The feedback and control system comprises:
at least one measurement element;
at least one processing element;
and at least one adjustment element configured to adjust the phase mismatch compensator (PMC).

In some embodiments, the apparatus further comprises at least one oven each configured to adjust the temperature of said nonlinear crystal (NLC).

In some embodiments, the length (LS) of the first nonlinear crystal is 10% or less of the length (LD) of the second nonlinear crystal (LS≤0.1LD).

In some embodiments, the second nonlinear crystal comprises LBO and the length (LD) of the second nonlinear crystal is 40 mm or greater.

In some embodiments, the fundamental frequency (FF) has the properties of infrared (IR) light (λF=1064 nm) and the second harmonic frequency (FH) has the properties of visible light (λH= 532 nm).

In some embodiments, each of said nonlinear crystals (NLCs) has a fundamental beam polarization along its crystal axis or at a 45 degree angle to its crystal axis. configured to have

In some embodiments, each of said nonlinear crystals (NLC) is at least one selected from the group consisting of BBO, KTP, LBO, CLBO, DKDP, ADP, KDP, LiIO3, KNbO3, LiNbO3, AgGaS2, and AgGaSe2. Contains one material.

In some embodiments, the dimensions of each lateral area of said nonlinear crystal (NLC) are larger than the dimensions of the input beam it receives.

In some embodiments, the apparatus further comprises at least one focusing element configured to focus the beam onto said nonlinear crystal (NLC).

In some embodiments of the invention,
A method for frequency doubling optical radiation, comprising:
providing a nonlinear crystal (NLC) having a fundamental beam at a fundamental frequency (FF) and a weak second harmonic beam at a second harmonic frequency (FH);
launching by the nonlinear crystal (NLC) an intense frequency-doubled beam at the second harmonic frequency (FH) together with the residual beam at the fundamental frequency (FF);
a power ratio between the weak second harmonic beam and the fundamental beam is less than 5×10 ⁻³ to 1;
A method is provided, wherein the power ratio of said strong frequency doubled beam and said fundamental beam is greater than 0.3:1.

In some embodiments,
the providing step further includes compensating for a phase mismatch between the fundamental beam and the weak second harmonic beam;
The method is
Further comprising controlling a phase mismatch compensator (PMC) to enable maximizing the output of said strong frequency doubled beam.

In some embodiments of the invention,
An apparatus configured to frequency-multiply an optical radiation input to provide an output beam at a second harmonic frequency, comprising:
at least two consecutive nonlinear crystals (NLCs), each of said nonlinear crystals receiving a first beam of fundamental frequency (FF) and optionally said first beam from the preceding nonlinear crystal (NLC); the nonlinear configured to receive a second beam at second harmonic frequency (FH) and to emit a strong frequency doubled beam at said second harmonic frequency (FH) together with a residual beam at said fundamental frequency (FF); a crystal (NLC);
at least one phase mismatch compensator (PMC) disposed between two said nonlinear crystals (NLCs), said fundamental frequency (FF) before being received by said subsequent nonlinear crystals (NLCs); the phase mismatch compensator (PMC) configured to correct a phase relationship between the residual beam and a second harmonic beam at the second harmonic frequency (FH);
A motorized rotation device provided for each of the phase mismatch compensators (PMCs), configured to actively rotate the phase mismatch compensators (PMCs), whereby the residual beam and said motorized rotating device for actively adjusting the correction of the phase relationship with said second harmonic beam.

In some embodiments, the apparatus samples an intense frequency-doubled beam and accordingly adjusts the phase mismatch compensator ( and at least one feedback and control system configured to tilt the PMC).

In some embodiments,
The feedback and control system comprises:
at least one beam splitter;
at least one measurement element;
at least one processing element;
at least one control element configured to control the motorized rotating device.

In some embodiments, the phase mismatch compensator (PMC) comprises an optically transparent window exhibiting chromatic dispersion, and the distance required for the beam to pass through the window is the angle of rotation of the window. is configured to vary relative to In some embodiments, the phase mismatch compensator (PMC) comprises a plate exhibiting chromatic dispersion (e.g., a transparent plate polished on both sides), the distance required for the beam to pass through the plate varies relative to the rotation angle of the plate.

In some embodiments, the motorized rotating device is configured to rotate the phase mismatch compensator (PMC) in stepped and/or continuous motion.

In some embodiments, the motorized rotating device is configured to rotate the phase mismatch compensator (PMC) in a dithered fashion bounded by upper and lower limits.

In some embodiments,
wherein the motorized rotating device is configured to rotate the phase mismatch compensator (PMC) in a dithered fashion bounded by upper and lower limits;
The feedback and control system uses the dither configuration to:
(a) minimizing the subsequent inversion in the nonlinear crystal (NLC), thereby maximizing the power of the output beam;
(b) maximizing the subsequent inversion in the nonlinear crystal (NLC), thereby minimizing the power of the output beam;
(c) adjusting the power of said output beam to a predetermined value between its maximum and minimum values;
is configured to provide at least one of

In some embodiments, the motorized rotator shifts the phase mismatch compensator (PMC) between a maximum harmonic conversion state and a minimum harmonic conversion state to turn the output beam on and off. , configured to rotate in toggle mode.

In some embodiments, the motorized rotating device rotates the phase mismatch compensator (PMC) to provide a flat top pulse with controlled rise and fall times and controllable duration. It is configured to allow

In some embodiments, the motorized rotating device is configured to provide shaped harmonic pulses by rotating the phase mismatch compensator (PMC) according to a lookup table.

In some embodiments, the apparatus further comprises at least one dichroic beam splitter configured to separate at least a portion of said residual beam from said output beam.

In some embodiments, the power ratio of said strong frequency doubled beam to said first beam at said fundamental frequency is greater than 0.3:1.

In some embodiments, the apparatus further comprises at least one oven each configured to adjust the temperature of said nonlinear crystal (NLC). In some embodiments, the apparatus further comprises at least two ovens each configured to adjust the temperature of said nonlinear crystal (NLC).

In some embodiments, the apparatus compensates for output fluctuations caused by temperature fluctuations of the oven housing the nonlinear crystal (NLC) by actively controlling the phase mismatch compensator (PMC). Configured to be minimal.

In some embodiments, at least one of the NLCs comprises an LBO and its length (LD) is sufficient to achieve significant harmonic light. In some embodiments, at least one of the NLCs comprises an LBO and has a length (LD) greater than 40 mm.

In some embodiments, the fundamental frequency (FF) has the properties of infrared (IR) light (λF=1064 nm) and the second harmonic frequency (FH) has the properties of visible light (λH= 532 nm).

In some embodiments, each of said nonlinear crystals (NLCs) has a fundamental beam polarization along its crystal axis or at a 45 degree angle to its crystal axis. configured to have

In some embodiments, each of said nonlinear crystals (NLC) is at least one selected from the group consisting of BBO, KTP, LBO, CLBO, DKDP, ADP, KDP, LiIO3, KNbO3, LiNbO3, AgGaS2, and AgGaSe2. Contains one material.

In some embodiments, the dimensions of each lateral area of said nonlinear crystal (NLC) are larger than the dimensions of the input beam it receives.

In some embodiments, the apparatus further comprises at least one focusing element configured to focus the beam onto said nonlinear crystal (NLC).

In some embodiments of the invention, a method for activating ("on") and/or deactivating ("off") a frequency doubled output beam from an apparatus as described above, comprising:
a sampling step that samples in real time and measures the output beam;
determining continuously or frequently whether the output beam has reached a maximum value (for "on" output) or a minimum value (for "off"output);
if the determination in the decision step is "no", then rotating the PMC, then stepping back to sampling and repeating the method;
If the decision in the decision step is "yes", then maintain the current PMC rotation angle αMAX (or αMIN) and then return to the sampling step to determine either the dynamic input beam and/or the dynamic oven temperature. and repeating the method for

The subject matter regarded as invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. The invention, however, both as to organization and method of operation, together with objects, features and advantages thereof, may best be understood by reading the following detailed description when read with the accompanying drawings in which: FIG. .

FIG. 1 schematically shows a prior art example of a coherent beam combining (CBC) system. FIG. 2 schematically illustrates a laser system comprising a seed laser device and a coherent beam combining (CBC) system configured to condition an amplified laser beam, according to some embodiments. FIG. 3 illustrates a seed laser device, a fast optical conditioner (FOM), and a coherent beam combining (CBC) system configured to condition an amplified laser beam, according to some embodiments; 1 schematically shows a laser system; FIG. 4 illustrates two seed laser devices, each providing a seed beam of a different wavelength, an optical switch, and a coherent beam combining (CBC) system to condition the amplified laser beam, according to some embodiments. 1 schematically illustrates a laser system configured to. FIG. 5 shows two seed laser devices each providing a seed beam of a different wavelength, an optical switch, and a coherent beam combining (CBC) system to condition the amplified laser beam, according to some embodiments. 1 schematically illustrates a laser system configured to. FIG. 6A schematically illustrates a laser system, according to some embodiments, comprising two seed laser devices each providing a seed beam of a different wavelength, an optical switch, a dichroic mirror, and coherent beam combining ( CBC) system and configured to condition an amplified laser beam. FIG. 6B schematically illustrates a laser system comprising two seed laser devices each providing a seed beam of a different wavelength, an optical switch, a dichroic mirror, and a master oscillator output amplifier, according to some embodiments. (MOPA) and configured to condition an amplified laser beam. FIG. 6C schematically illustrates a laser system, according to some embodiments, comprising two seed laser devices each providing a seed beam of a different wavelength, an optical switch, a dichroic mirror, and coherent beam combining ( CBC) system and configured to condition an amplified laser beam. FIG. 7A shows a seed laser device, an optical polarization combiner (OPC), a polarizing beam splitter (PBS), and a coherent beam combiner (CBC) system to condition an amplified laser beam, according to some embodiments. 1 schematically illustrates a laser system configured to. FIG. 7B comprises a seed laser device, an optical polarization combiner (OPC), a polarizing beam splitter (PBS), and a master oscillator power amplifier (MOPA) to condition an amplified laser beam, according to some embodiments. 1 schematically illustrates a laser system configured to. FIG. 8A schematically illustrates an optical polarization combiner (OPC), according to some embodiments. FIG. 8B schematically illustrates another optical polarization combiner (OPC), according to some embodiments. FIG. 9 schematically shows a prior art example of a fiber amplification system. FIG. 10A schematically illustrates a hybrid pump module, according to various embodiments of the invention. FIG. 10B schematically illustrates a hybrid pump module, according to various embodiments of the invention. FIG. 10C schematically illustrates a hybrid pump module, according to various embodiments of the invention. FIG. 10D schematically illustrates a hybrid pump module, according to various embodiments of the invention. FIG. 11A schematically illustrates a hybrid pump module in which the core-related module is the seed-related module, according to some embodiments of the invention. FIG. 11B schematically illustrates a hybrid pump module in which the core-related module is the seed-related module, according to some embodiments of the invention. FIG. 11C schematically illustrates a hybrid pump module in which the core-related module is the seed-related module, according to some embodiments of the invention. FIG. 12 schematically illustrates a hybrid pump module in which the core-associated module is the output module, according to some embodiments of the invention. FIG. 13 schematically illustrates a hybrid pump module in which the core-related module is a highly reflective module, according to some embodiments of the invention. FIG. 14 schematically illustrates a hybrid pump module in which the core-related modules are partially reflective modules, according to some embodiments of the present invention. FIG. 15 schematically illustrates a fiber amplification system, according to some embodiments of the invention. Figures 16A and 16B schematically illustrate fiber laser systems, according to some embodiments of the present invention. Figure 17A schematically shows some setups for an apparatus for frequency doubling an emitted laser beam, according to some embodiments of the present invention. Figure 17BC schematically shows some setups for an apparatus for frequency doubling an emitted laser beam, according to some embodiments of the present invention. Figure 17C schematically shows some setups for an apparatus for frequency doubling an emitted laser beam, according to some embodiments of the present invention. FIG. 18(A) shows the optical axis of a single crystal placed in an oven when set up for low power frequency doubling but operated at high power according to some embodiments of the present invention. Schematically shows an example of temperature change along . FIG. 18B schematically shows an example of the phase difference between the fundamental beam and the multiplied beam accumulated up to each point in the crystal. Figures 19(A)-(C) schematically illustrate the temperature reconditioning of the PFD after applying a second harmonic seed beam with conjugate phase difference to achieve minimum MP and optimum temperature in the focal region. show. FIG. 20A shows a simulation overview using a 500 W input beam and a 50 mm seeder crystal. FIG. 20B shows a simulation summary using a 500 W input beam and a 50 mm seeder crystal. FIG. 20C shows a simulation summary using a 500 W input beam and a 50 mm seeder crystal. FIG. 21 shows a seeder beam profile at a non-resonant temperature, according to some embodiments of the present invention. FIG. 22A shows simulation results and a comparison thereof with and without a seeder beam, according to some embodiments of the present invention. FIG. 22B shows simulation results with and without a seeder beam and a comparison thereof, according to some embodiments of the present invention. FIG. 23 illustrates the added value of using seeder beams according to some embodiments of the present invention. FIG. 24 shows that the seeder beam provides phase effects by presenting a green output beam versus PMC rotation, according to some embodiments of the present invention. Figure 25A schematically illustrates various configurations of frequency doubling devices, according to some embodiments of the present invention. Figure 25B schematically illustrates various configurations of frequency doubling devices, according to some embodiments of the present invention. Figure 25C schematically illustrates various configurations of frequency doubling devices, according to some embodiments of the present invention. Figure 26 schematically illustrates the rotation or tilt angle of a PMC, with Figure 26(A) being a front view and Figure 26(B) being a side view, according to some embodiments of the present invention. FIG. 27 schematically illustrates an optional feedback algorithm used to continuously adjust the rotation angle of the PMC, according to some embodiments of the invention. FIG. 28A schematically illustrates variations in crystal temperature and multiplied output over time due to oven controller undershoot/overshoot, according to some embodiments of the present invention. FIG. 28B schematically illustrates variations in crystal temperature and multiplied output over time due to oven controller undershoot/overshoot, according to some embodiments of the present invention. FIG. 29 schematically illustrates output stabilization with dither control for rotating PMCs configured to overcome oven undershoot/overshoot, according to some embodiments of the present invention. FIG. 30 shows experimental results of dither control with feedback used to optimize the angle of the PMC after changing operating conditions, according to some embodiments of the present invention. Figures 31 (A) and (B) show experimental results of maintaining the harmonic output at a maximum value while reducing variation with static or dynamic PMC, according to some embodiments of the present invention. FIG. 32 shows the harmonic output spectra for a one hour run with and without the stabilization algorithm, according to some embodiments of the present invention. FIG. 33 schematically illustrates inverse transform phase difference, according to some embodiments of the present invention. FIG. 34A compares the rise time achieved by turning on the laser quickly as shown in FIG. 34A with the rise time achieved by toggling the position of the PMC, according to some embodiments of the present invention. indicates FIG. 34B compares the rise time achieved by turning on the laser quickly as shown in FIG. 34A with the rise time achieved by toggling the position of the PMC, according to some embodiments of the present invention. indicates

It will be appreciated that the illustrated elements are not necessarily drawn to scale for simplicity and clarity of illustration. For example, the dimensions of some elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements.

In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, and components have not been described in detail so as not to obscure the present invention.

As used herein, in one embodiment, the term "about" refers to ±10%. In another embodiment, the term "about" refers to ±9%. In another embodiment, the term "about" refers to ±8%. In another embodiment, the term "about" refers to ±7%. In another embodiment, the term "about" refers to ±6%. In another embodiment, the term "about" refers to ±5%. In another embodiment, the term "about" refers to ±4%. In another embodiment, the term "about" refers to ±3%. In another embodiment, the term "about" refers to ±2%. In another embodiment, the term "about" refers to ±1%.

Method and system for conditioning a laser beam

The present invention relates to methods and apparatus for manipulating and conditioning laser beams from lasers, laser beam arrays, and optical fiber arrays. More specifically, the present invention enables the laser system to maintain its operating power, e.g., without turning off or reducing the power of the laser system, or interrupting the seed laser beam. , provides a method and apparatus for enabling activation/deactivation of a laser beam. This can save (reduce) operating time by means of allowing higher operating frequencies (e.g. the tuning frequency can reach 10 GHz) without damaging components such as e.g. amplifiers. .

A Coherent Beam Combining (CBC) system, an example of a laser amplification system, is disclosed in US Patent Application Publication No. 2013/0107343. This patent document describes a laser system comprising a seed laser and an optical amplification subsystem for receiving the output of the seed laser and providing an amplified laser output, the optical amplification subsystem comprising a first plurality of Amplification assemblies including a first plurality of amplification assemblies each having a second plurality of optical amplification assemblies, and a plurality of phase adjusters associated with each of the first plurality of amplification assemblies. A phase control circuit is disclosed.

FIG. 1 shows a general or typical model/design of coherent beam combining (CBC). This laser system 1100 comprises a seed laser 1110 configured to provide a seed beam to a coherent beam combining (CBC) system 1101 . CBC system 1101 includes a first optical amplifier 1121 that receives the output of seed laser 1110 and provides an amplified first output beam. The first output beam is split into a first plurality of input beams by a first beamsplitter 1131 and the split first plurality of input beams is coupled by a second plurality of optical amplifiers 1122 arranged in parallel. Received. A second plurality of optical amplifiers 1122 is configured to provide an amplified second plurality of output beams. The second plurality of output beams are then split by a second plurality of beamsplitters 1132 . The split second plurality of input beams are received by a third plurality of optical amplifiers 1123 arranged in parallel. A third plurality of optical amplifiers 1123 is configured to provide an amplified third plurality of output beams. The amplified third plurality of output beams are then coherently combined into a single CBC output beam 1170 . Coherent combining can be provided, for example, by at least one beam combiner 1140 configured to provide CBC output beams 1170 by generating beam interference at locations indicated as CBC points 1171 . Alternatively, coherent beam combining can be provided in free space (collimated free space without the use of a beam combiner; not shown) where beam interference occurs at a location indicated as CBC point 1171 .

The CBC system further comprises a phase control circuit 1160 including a plurality of phase adjusters 1150 associated with each of the second plurality of input beams. A phase control circuit 1160 monitors beam interference at CBC point 1171 and adjusts the phase of each of the second plurality of input beams by a plurality of phase adjusters 1150 such that constructive beam interference occurs at CBC point 1171 . is configured to control Note that all optical connections are provided by optical fibers 1102 . Also, optical amplifiers 1121, 1122, 1123 may be configured to have intensity characteristics that are the same or different from each other, and beam combiner 1140 is described in FIGS. 4A and 4B of US2013/0107343. Note that it may be configured as described.

Pulsed operation of a laser refers to any laser not classified as continuous wave (CW) such that the light output appears in pulses of predetermined duration at a predetermined repetition rate. This use of laser waves encompasses a wide range of techniques to address various motivations. Some lasers are pulsed for the simple reason that they cannot operate in continuous mode. In other cases, the application requires the generation of pulses with as much energy as possible. Since the pulse energy is equal to the average power divided by the repetition rate, this goal can be achieved by decreasing the pulse rate so that more energy can be stored between pulses. Other applications rely on the peak pulse power (rather than the energy of the pulse) to specifically obtain nonlinear optical effects. In this case, for a given pulse energy, it is necessary to generate pulses of the shortest possible duration. Quasi-continuous wave (QCW) operation of a laser is short enough to significantly reduce thermal effects, but brings the laser process closer to its steady state, i. means to turn the pump source "on" for a predetermined time interval long enough to The duty cycle (percentage of "on" time) can be, for example, a few percent. This can significantly reduce heating and all associated thermal effects, such as thermal lensing and overheating damage. Thus, QCW operation allows operation at higher power peak power at the expense of lower average power. Source: "https://en.wikipedia.org/wiki/Pulsed_laser; (see also https://en.wikipedia.org/wiki/Wikipedia: Text of Creative Commons Attribution -ShareAlike 3.0 Unported License)".

Those skilled in the art will understand that the term "fast optical modulator (FOM)" is an electro-optic modulator configured to be used to control the power, phase or polarization of a laser beam using an electrical control signal. (EOM) (or electro-optic modulator). In some embodiments, the principle of operation is based on the linear electro-optic effect (also called Pockels effect), that is, the refractive index of a nonlinear crystal is changed by an electric field in proportion to the field strength.

Those skilled in the art will understand that the term "phase adjuster" refers to an optical adjuster used to control the optical phase of a laser beam. Commonly used types of phase adjusters, such as electro-optic adjusters based on Pockels cells and liquid crystal adjusters, utilize, for example, thermally induced refractive index changes or length changes in optical fibers. Alternatively, it is possible to induce a change in the length of the optical fiber by drawing. Various types of phase adjusters are used in the field of integrated optics to propagate modulated light through waveguides.

Those skilled in the art will understand that the term "master oscillator power amplifier (MOPA)" refers to a structure consisting of a master laser (or seed laser) and an optical amplifier to boost power. In some embodiments the power amplifier is a fiber device. In other embodiments, the MOPA may consist of a solid-state bulk laser and a bulk amplifier, or a tunable external cavity diode laser and a semiconductor optical amplifier.

Those skilled in the art will recognize that the term "beam splitter" is configured to split an incident light beam (e.g., a laser beam) into two or more beams that may or may not have the same optical power as each other. It will be understood to refer to an optical device. In some embodiments, beam splitters are used as beam combiners to combine several beams into a single beam. In some embodiments, beamsplitters are required in interferometers, autocorrelators, cameras, projectors, and laser systems.
In some embodiments, the beam splitter can include at least one of dielectric mirrors, cubes, fiber optic splitters, planar lightwave circuit (PLC) splitters, diffraction gratings, and multimode interference (MMI). .
A dielectric mirror can be any partially reflective mirror that can be used to split a light beam. In laser technology, dielectric mirrors are often used for this purpose. The angle of incidence determines the angular separation of the output beams, which affects the properties of the beamsplitter, eg, 45 degrees (this value is often convenient, but other values are possible). A wide range of power division ratios can be achieved with various designs of dielectric coatings.
The cube splits the beam at its interfaces. Cubes are often made by gluing two triangular glass prisms together with clear resin or cement. The thickness of the layer can be used to adjust the power split ratio for a given wavelength.
A fiber optic splitter is a type of fiber optic coupler that is used as a fiber optic beam splitter. Such devices may be made by fusion splicing optical fibers and may have more than one output port. As with bulk devices, the splitting ratio may or may not be strongly dependent on the wavelength and polarization of the input.
A PLC is either an integrated optical circuit (IC) or an optical circuit board made with optical waveguides to route photons.
A diffraction grating is an optical element having a repeating structure that splits and diffracts light into multiple beams traveling in different directions. The direction of travel of these beams depends on the grating spacing and the wavelength of the light. In some embodiments, diffraction gratings can also be used as beam combiners.
Multimode interference (MMI) is an optical waveguide with a spatially non-uniform structure for guiding light, i.e. limiting the spatial region in which light propagates. MMIs can be used, for example, for splitting and combining light beams in integrated optical interferometers.

Those skilled in the art will appreciate that the term "fiber coupler" or "coupler" refers to an optical fiber device having one or more input fibers and one or more output fibers. Light from an input fiber can appear at one or more outputs, with an output distribution potentially dependent on wavelength and polarization.

Those skilled in the art will appreciate that the term "TAP" refers to couplers configured for combined power ratios of 50:50, 75:25, 90:10, or 99:1. be. Fiber tapping can use a network tap method that extracts the signal from the optical fiber without breaking the connection. Tapping an optical fiber allows part of the signal being transmitted in the core of the fiber to be diverted to another fiber or detector.

Those skilled in the art will appreciate that the terms "beam interference" or "interference" refer to the phenomenon of superimposing two or more light waves to form a combination of greater, lower, or equal amplitude. be. If the sum is greater than either of the original two waves, it is called "constructive interference". If the sum of the two original waves is less than one, even zero, it is called "destructive interference".

Those skilled in the art will understand that the term "optical amplifier" refers to a device that transmits an input signal and produces an output signal having a higher optical power. In some embodiments, the input and output are laser beams propagated in free space or in fibers. Amplification takes place within a so-called gain medium, which must be "pumped" (ie supplied with energy) from an external source. In some embodiments, the optical amplifier is optically, chemically, or electrically pumped.

Those skilled in the art will appreciate that the term "dichroic mirror" refers to a mirror that has significantly different reflective or transmissive properties at two different wavelengths.

Those skilled in the art will appreciate that the term "seed laser" in some embodiments of the present invention refers to the output of a laser that is injected into an amplifier or another laser. Typical types of seed lasers are miniature laser diodes (single-frequency or gain-switched), short-cavity fiber lasers, and miniature solid-state lasers such as non-planar ring oscillators (NPROs).

Reference is now made to FIG. FIG. 2 illustrates a laser system 1200 configured to provide and condition a laser beam 1270 (more specifically a high power laser beam), according to some embodiments of the invention.
This laser system 1200 is
a coherent beam combining (CBC) system 1201;
at least one seed laser device 1210 configured to provide at least one input seed beam to the CBC system 1201;
Output laser beam 1270 is selectively provided by CBC system 1201 .

In some embodiments of the invention, the components of the CBC system can come in a variety of designs and configurations, some of which are known in the art, non-limiting examples of which are: CBC system 1101 as shown in FIG. 1, or another non-limiting example is CBC system 1201 as shown in FIG.
The CBC system 1201 shown in FIG.
a plurality of phase adjusters 1250;
at least one control circuit 1260;
A plurality of phase adjusters 1250, a seed beam provided from a seed laser apparatus 1210, a plurality of optical amplifiers 1220, each arranged to allow constructive or destructive beam interference at a CBC point 1271, at least One beam splitter 1230, and optionally at least one beam combiner 1240 (beam coherent combining may be provided without the use of beam combiners, e.g., with collimated free space (not shown)). ), directly or indirectly (e.g., by an optical fiber 1202), and
At least one control circuit 1260 monitors beam interference at CBC point 1271 and controls at least one of the plurality of phase adjusters 1250 accordingly to provide constructive or destructive beam interference. is configured as

In some embodiments, laser system 1200 includes:
To activate laser beam 1270 (in other words, when laser beam 1270 is requested to be turned “on”), by control circuit 1260 to allow constructive interference at CBC point 1271 controlling phase adjuster 1250 thereby providing output laser beam 1270;
To deactivate laser beam 1270 (in other words, when laser beam 1270 is requested to be turned “off”), control circuit 1260 allows destructive interference at CBC point 1271 . controlling phase adjuster 1250 by to thereby stop providing output laser beam 1270;
is configured to provide fast and effective modulation of the output laser beam 1270 according to a method comprising:

In some embodiments, the above step of controlling the phase adjuster to allow constructive interference includes adjusting the phase adjuster to provide the laser beam at CBC point 1271 at maximum intensity. .
In some related embodiments, the above step of controlling the phase adjusters to allow destructive interference is performed by adjusting the phase adjusters 1250 already adjusted to provide the laser beam at maximum intensity. Control the half and include steps for the laser beam.
In other related embodiments, the above step of controlling the phase adjusters to allow destructive interference is performed by adjusting some of the phase adjusters 1250 already adjusted to provide the laser beam at maximum intensity. and adjusting the Each adjustment of phase adjusters 1250 may be identical to each other or may be different from each other.
In some embodiments, constructive interference is considered when the laser intensity is greater than about 50% of the maximum intensity. Preferably, constructive interference is considered when the laser intensity is about 100% of the maximum intensity. In some embodiments, destructive interference is considered when the laser intensity is below the maximum intensity. Preferably, constructive interference is considered when the laser intensity is about 0% of the maximum intensity.

In some other related embodiments, the method includes adjusting (by control circuit 1260) some of the phase adjusters that have already been adjusted to provide the laser beam at maximum intensity. Further including adjusting the beam 1270 . Adjustment of the phase adjuster adjusts the intensity of the output laser beam 1270 to a predetermined percentage of maximum intensity between 0% and 100% (e.g., 5%, 10%, 25%, 50%, 75%, 90%, 95%, or any other percentage).

In some embodiments, the above step of controlling the phase adjuster to allow destructive interference includes adjusting the phase adjuster to provide the laser beam at CBC point 1271 at minimum intensity. .

Next, refer to FIG. FIG. 3 illustrates another laser system 1300 configured to provide and condition a laser beam 1370 (more specifically, a high power laser beam), according to some embodiments of the present invention.
This laser system 1300
at least one seed laser device 1310;
a fast optical modulator (FOM) 1316 configured to receive the seed laser beam of the seed laser device and adjust its bandwidth;
a coherent beam combining (CBC) system 1301 configured to receive a bandwidth-tuned seed beam and provide an amplified laser beam 1370;
Prepare.

In some embodiments, modulation by the fast optical modulator (FOM) 1316 is two predetermined bandwidths, a first bandwidth (Δω1) and a second bandwidth that is greater than the first bandwidth. (Δω2; Δω2>Δω1).

In some embodiments, the first bandwidth (Δω1) has a coherence length Lc1 longer than the root mean square (RMS) of the optical path difference (OPD) between different channels in the system (Lc1>OPD ) and the second bandwidth (Δω2) is chosen such that its coherence length Lc2 is less than the root mean square (RMS) of the OPD between different channels in the system (Lc2<OPD). be.

In some embodiments of the invention, the components of the CBC system can come in a variety of designs and configurations, some of which are known in the art, non-limiting examples of which are: CBC system 1101 as shown in FIG. 1, or another non-limiting example is CBC system 1301 as shown in FIG.
The CBC system 1301 shown in FIG.
a plurality of phase adjusters 1350;
at least one control circuit 1360;
A plurality of phase adjusters 1350, a seed beam provided from a seed laser apparatus 1310, a plurality of optical amplifiers 1320, each arranged to allow constructive or destructive beam interference at a CBC point 1371, at least One beam splitter 1330, and optionally at least one beam combiner 1340 (beam coherent combining may be provided without the use of beam combiners, e.g., with collimated free space (not shown)). configured to be optically connected, either directly or indirectly (e.g., by an optical fiber), to
At least one control circuit 1360 monitors beam interference at CBC point 1371 and controls at least one of the plurality of phase adjusters 1250 accordingly to provide constructive or destructive beam interference. is configured as

In some embodiments, laser system 1300 includes:
To activate laser beam 1370, FOM 1316 is controlled to provide a seed laser beam having a narrow bandwidth (Δω1) set to allow constructive interference at CBC point 1371, thereby , providing an output laser beam 1370;
To deactivate laser beam 1370, FOM 1316 is configured to provide a seed laser beam with a wide bandwidth (Δω2; Δω2>Δω1) set to disable constructive interference at CBC point 1371. controlling, thereby ceasing to provide the output laser beam 1370;
is configured to provide fast and effective modulation of the output laser beam 1370 according to a method comprising:

In some embodiments, the above steps of controlling FOM 1316 to provide a seed laser beam with a narrow bandwidth are performed by control circuitry 1360 to enable constructive interference at CBC point 1371. further comprising controlling 1350;

In some embodiments, the above step of controlling the phase adjuster to provide constructive beam interference includes adjusting the phase adjuster to provide constructive beam interference at maximum intensity.

In some embodiments, constructive interference is considered when the laser intensity is greater than about 50% of the maximum intensity. Preferably, constructive interference is considered when the laser intensity is about 100% of the maximum intensity. In some embodiments, destructive interference is considered when the laser intensity is below the maximum intensity. Preferably, constructive interference is considered when the laser intensity is about 0% of the maximum intensity.

In some embodiments, control of FOM 1316 is provided by at least one control circuit 1360 of CBC system 1301 . In other embodiments, control of FOM 1316 is provided by higher level control circuitry 1361 configured to control both FOM 1316 and at least one control circuitry 1360 of CBC system 1301 .

Next, refer to FIG. FIG. 4 illustrates another laser system 1400 configured to provide and condition a laser beam 1470 (more specifically a high power laser beam), according to some embodiments of the present invention.
This laser system 1400 is
a coherent beam combining (CBC) system 1401 configured to receive a seed laser beam and provide an amplified laser beam 1470;
a first seed laser apparatus 1410 configured to provide a first seed beam having a first wavelength (λ1);
a second seed laser apparatus 1411 configured to provide a second seed beam having a second wavelength (λ2; λ2≠λ1) different from the first wavelength;
an optical switch 1415 configured to link only one of the first seed laser beam and the second seed laser beam to the CBC system 1401;
Output laser beam 1470 is provided by CBC system 1401 .

In some embodiments of the invention, the components of the CBC system can come in a variety of designs and configurations, some of which are known in the art, non-limiting examples of which are: CBC system 1101 as shown in FIG. 1, or another non-limiting example is CBC system 1401 as shown in FIG.
The CBC system 1401 shown in FIG.
a plurality of phase adjusters 1450;
at least one control circuit 1460;
A plurality of phase adjusters 1350, linked (first or second) seed beams, a plurality of optical amplifiers, each arranged to enable constructive or destructive beam interference at CBC point 1471 1420, at least one beam splitter 1430, and optionally at least one beam combiner 1440 (beam coherent combining may be provided without the use of beam combiners, e.g. ) is configured to be optically connected, either directly or indirectly (e.g., by an optical fiber), to
At least one control circuit 1460 is configured to monitor beam interference at CBC point 1471 and control at least one of the plurality of phase adjusters accordingly.

In some embodiments, phase adjuster 1450 does not provide constructive beam interference at CBC point 1471 when adjusted to allow constructive beam interference based on the first wavelength (λ1). A second wavelength (λ2) is selected as such.

In some embodiments, at least one beam combiner 1440 combines beams having a particular wavelength, i.e., a first wavelength (λ1), and beams having other wavelengths, including a second wavelength (λ2). A wavelength sensitive diffractive optical element (DOE) configured to scatter. A non-limiting example of such a beam combiner is a Dammann grating, in which the optimal angle between the combined beams is very sensitive to wavelength. The beam is therefore configured to achieve maximum coupling efficiency for the first seed laser beam having the first wavelength (λ1). Therefore, when the seed laser light is switched to a second laser light having a second wavelength (λ2; λ2≠λ1), the coupling efficiency is reduced, thereby disabling the output of laser beam 1470 .

In some embodiments, laser system 1400 includes:
Control circuitry 1460 to control optical switch 1415 to link the first seed beam to CBC system 1401 to activate laser beam 1470 and to allow constructive interference at CBC point 1471. controlling phase adjuster 1450 by to thereby provide output laser beam 1470;
To deactivate laser beam 1470 , optical switch 1415 is controlled (without adjusting phase adjuster 1450 ) to link the second seed beam to CBC system 1401 for constructive interference at CBC point 1471 . and thereby stop providing the output laser beam 1470;
is configured to provide fast and effective modulation of the output laser beam 1470 according to a method comprising:

For clarity, after activating laser beam 1470, phase adjuster 1450 is configured to allow constructive interference at CBC point 1471 based on the first wavelength (λ1) of the first seed laser beam. , and optical switch 1415 links a second seed laser beam having a second wavelength (λ2; λ2≠λ1), no constructive interference occurs because phase adjuster 1450 is not readjusted. , which makes constructive interference impossible. Thus, when optical switch 1415 relinks the first seed laser light having the first wavelength (λ1), phase adjuster 1450 is already adjusted.

In some embodiments, λ1 and λ2 are selected such that their difference (λ2≠λ1) allows beam activation/deactivation according to the embodiments and their selected features described above. be done.

In some embodiments, the above step of controlling phase adjuster 1450 to provide constructive beam interference includes adjusting the phase adjuster to provide constructive beam interference at maximum intensity.

In some embodiments, constructive interference is considered when the laser intensity is greater than about 50% of the maximum intensity. Preferably, constructive interference is considered when the laser intensity is about 100% of the maximum intensity. In some embodiments, destructive interference is considered when the laser intensity is below the maximum intensity. Preferably, constructive interference is considered when the laser intensity is about 0% of the maximum intensity.

In some embodiments, control of optical switch 1415 is provided by at least one control circuit 1460 of CBC system 1401 . In other embodiments, control of optical switch 1415 is provided by higher level control circuitry 1461 configured to control both optical switch 1415 and at least one control circuitry 1460 of CBC system 1401 .

Reference is now made to FIG. FIG. 5 illustrates another laser system 1500 configured to provide and condition a laser beam 1570 (more specifically a high power laser beam), according to some embodiments of the present invention.
This laser system 1500
a coherent beam combining (CBC) system 1501 configured to receive a seed laser beam and provide an amplified laser beam;
a first seed laser apparatus 1510 configured to provide a first seed laser beam having a narrow bandwidth (Δω1);
a second seed laser apparatus 1511 configured to provide a second seed laser beam having a wider bandwidth than the first wavelength (Δω2; Δω2>Δω1);
an optical switch 1515 configured to link only one of the first seed laser beam and the second seed laser beam to the CBC system 1501;
The narrow bandwidth (Δω1) is set to allow constructive beam interference at CBC point 1571 of CBC system 1501,
A wide bandwidth (Δω2) is set to disable constructive beam interference at CBC point 1571,
Output laser beam 1570 is provided by CBC system 1501 .

In some embodiments, the first bandwidth (Δω1) has a coherence length Lc1 longer than the root mean square (RMS) of the optical path difference (OPD) between different channels in the system (Lc1>OPD ) and the second bandwidth (Δω2) is chosen such that its coherence length Lc2 is less than the root mean square (RMS) of the OPD between different channels in the system (Lc2<OPD). be.

In some embodiments of the invention, the components of the CBC system can come in a variety of designs and configurations, some of which are known in the art, non-limiting examples of which are: CBC system 1101 as shown in FIG. 1, or another non-limiting example is CBC system 1501 as shown in FIG.
The CBC system 1501 shown in FIG.
a plurality of phase adjusters 1550;
at least one control circuit 1560;
A plurality of phase adjusters 1550, linked (first or second) seed beams, a plurality of optical amplifiers each arranged to enable constructive or destructive beam interference at CBC point 1571 1520, at least one beam splitter 1530, and optionally at least one beam combiner 1540 (beam coherent combining may be provided without the use of beam combiners, e.g. ) is configured to be optically connected, either directly or indirectly (e.g., by an optical fiber), to
At least one control circuit 1560 is configured to monitor beam interference at CBC point 1571 and control at least one of the plurality of phase adjusters accordingly.

In some embodiments, laser system 1500 includes:
To activate laser beam 1570, optical switch 1515 is controlled to link the first seed laser beam to CBC system 1501 to allow constructive interference at CBC point 1571, thereby output laser beam 1570 and
To deactivate laser beam 1570, optical switch 1515 is controlled to link the second seed laser beam to CBC system 1501 to disable constructive interference at CBC point 1571, thereby rendering the output laser beam discontinuing the provision of 1570;
is configured to provide fast and effective modulation of the output laser beam 1570 according to a method comprising:

In some embodiments, the above step of activating laser beam 1570 further includes controlling phase adjuster 1550 by control circuit 1560 to allow constructive interference at CBC point 1571 .

In some embodiments, the above step of controlling phase adjuster 1550 to provide constructive beam interference includes adjusting the phase adjuster to provide constructive beam interference at maximum intensity.

In some embodiments, constructive interference is considered when the laser intensity is greater than about 50% of the maximum intensity. Preferably, constructive interference is considered when the laser intensity is about 100% of the maximum intensity. In some embodiments, destructive interference is considered when the laser intensity is below the maximum intensity. Preferably, constructive interference is considered when the laser intensity is about 0% of the maximum intensity.

In some embodiments, control of optical switch 1515 is provided by at least one control circuit 1560 of CBC system 1501 . In other embodiments, control of optical switch 1515 is provided by higher level control circuitry 1561 configured to control both optical switch 1515 and at least one control circuitry 1560 of CBC system 1501 .

Reference is now made to FIGS. 6A and 6C. 6A and 6C illustrate another laser system 1600A/1670A/1670C configured to provide and condition a laser beam 1670A/1670C (more specifically, a high power laser beam), according to some embodiments of the present invention. 1600C is shown.

The system 1600A shown in FIG. 6A includes:
a coherent beam combining (CBC) system 1601A configured to receive a seed beam and provide an amplified laser beam 1672A;
a first seed laser 1610 configured to provide a first seed beam having a first wavelength (λ1);
a second seed laser 1611 configured to provide a second seed beam having a second wavelength (λ2; λ2≠λ1) different from the first wavelength;
an optical switch 1615 configured to link only one of the first seed beam and the second seed beam to the CBC system 1601A;
Amplified laser beam 1672A is received, a beam having a first wavelength (λ1) is transmitted to the output of laser system 1600A, and a beam having a second wavelength (λ2) is reflected, thereby output laser beam 1670A and a dichroic mirror 1680A configured to selectively provide a .

In some embodiments, first wavelength (λ1), second wavelength (λ2), and dichroic mirror 1680A are dichroic if amplified laser beam 1672A has first wavelength (λ1). If mirror 1680A passes more than 50% (preferably about 100%) of the beam and amplified laser beam 1672A has a second wavelength (λ2), then dichroic mirror 1680A passes more than 50% (preferably about 100%) of the beam. is selected to reflect about 100%).

The system 1600C shown in FIG. 6C includes:
a coherent beam combining (CBC) system 1601C configured to receive the seed beam and provide an amplified laser beam 1672C;
a first seed laser 1610 configured to provide a first seed beam having a first wavelength (λ1);
a second seed laser 1611 configured to provide a second seed beam having a second wavelength (λ2; λ2≠λ1) different from the first wavelength;
an optical switch 1615 configured to link only one of the first seed beam and the second seed beam to the CBC system 1601C;
Amplified laser beam 1672C is received, a beam having a first wavelength (λ1) is transmitted to the output of laser system 1600C, and a beam having a second wavelength (λ2) is reflected, thereby output laser beam 1670C a dichroic mirror 1680C configured to selectively provide a .

In some embodiments, the first wavelength (λ1), the second wavelength (λ2), and the dichroic mirror 1680C are dichroic if the amplified laser beam 1672C has the first wavelength (λ1). If mirror 1680C passes more than 50% (preferably about 100%) of the beam and amplified laser beam 1672C has a second wavelength (λ2), then dichroic mirror 1680C passes more than 50% (preferably about 100%) of the beam. is selected to reflect about 100%).

In some embodiments of the invention, the components of the CBC system can come in a variety of designs and configurations, some of which are known in the art, non-limiting examples of which are: CBC system 1101 as shown in FIG. 1, or another non-limiting example is CBC system 1601A as shown in FIG. 6A.
The CBC system 1601A shown in FIG. 6A includes
a plurality of phase adjusters 1650;
at least one control circuit 1660;
A plurality of phase adjusters 1650, linked (first or second) seed beams, a plurality of optical amplifiers each arranged to enable constructive or destructive beam interference at CBC point 1671 1620, at least one beam splitter 1630, and optionally at least one beam combiner 1640, configured to be optically connected, either directly or indirectly,
At least one control circuit 1660 is configured to monitor beam interference at CBC point 1671A and control at least one of the plurality of phase adjusters accordingly.

In some embodiments, in a CBC system 1601A including at least one beam combiner 1640 shown in FIG. 6A, dichroic mirror 1680A is positioned beyond CBC point 1671A. In some embodiments, dichroic mirror 1680A may be positioned in front of the CBC point.

In another embodiment of the invention, the CBC system 1601C, shown in FIG. 6C,
a plurality of phase adjusters 1650;
at least one control circuit 1660;
A plurality of phase adjusters 1650 are linked (first or second) arranged to enable constructive beam interference at CBC point 1671C located in the far field in this embodiment. configured to be directly or indirectly optically connected to the seed beam, the plurality of optical amplifiers 1620, and the at least one beam splitter 1630 so that beam combining is in free space (collimated free space); configured to be
At least one control circuit 1660 is configured to monitor beam interference at CBC point 1671 and control at least one of the plurality of phase adjusters accordingly.

In the embodiment shown in FIG. 6C, dichroic mirror 1680C is positioned in front of CBC point 1671C.

In some embodiments, the laser system 1600A/1600C shown in FIGS. 6A and 6C
To activate laser beam 1670A/1670C, optical switch 1615 is controlled to link the first seed laser beam to CBC system 1601A/1601C to transmit output laser beam 1670A/1670C, thereby activating output laser beam 1670A/1670C. providing beams 1670A/1670C;
To deactivate laser beam 1670A/1670C, optical switch 1615 is controlled to link the second seed laser beam to CBC system 1601A/1601C to reflect output laser beam 1670A/1670C, thereby reducing the output ceasing to provide laser beam 1670A/1670C;
is configured to provide fast and effective adjustment of the output laser beam 1670A/1670C according to a method comprising:

In some embodiments, the method further includes controlling phase adjuster 1650 by control circuit 1660 to allow constructive interference at CBC points 1671A/1671C. In some embodiments, the above step of controlling the phase adjuster is performed only during the above step of activating the laser beam and not during the above step of deactivating the laser beam.

In some embodiments, the above step of controlling phase adjuster 1650 to provide constructive beam interference includes adjusting the phase adjuster to provide constructive beam interference at maximum intensity.

In some embodiments, constructive interference is considered when the laser intensity is greater than about 50% of the maximum intensity. Preferably, constructive interference is considered when the laser intensity is about 100% of the maximum intensity. In some embodiments, destructive interference is considered when the laser intensity is below the maximum intensity. Preferably, constructive interference is considered when the laser intensity is about 0% of the maximum intensity.

In some embodiments, control of optical switch 1615 is provided by at least one control circuit 1660 of CBC system 1601A/1601C. In other embodiments, control of optical switch 1615 is provided by a higher level control circuit 1661 configured to control both optical switch 1615 and at least one control circuit 1660 of CBC system 1601A/1601C.

Reference is now made to FIG. 6B. FIG. 6B shows laser system 1600B configured to provide and condition laser beam 1670B.
This laser system 1600B
a master oscillator power amplifier (MOPA) 1620B configured to receive the seed beam and provide an amplified laser beam 1672B;
a first seed laser 1610B configured to provide a first seed laser beam having a first wavelength (λ1);
a second seed laser 1611B configured to provide a second seed laser beam having a second wavelength (λ2; λ2≠λ1) different from the first wavelength;
an optical switch 1615B configured to link only one of the first seed laser beam and the second seed laser beam to the MOPA 1620B;
Amplified laser beam 1672B is received, a beam having a first wavelength (λ1) is transmitted to the output of laser system 1600B, and a beam having a second wavelength (λ2) is reflected, thereby output laser beam 1670B a dichroic mirror 1680B configured to selectively provide a .

The laser system 1600B is
controlling optical switch 1615B to link the first seed beam to MOPA 1620B to transmit laser beam 1670B to activate laser beam 1670B, thereby providing laser beam 1670;
controlling optical switch 1615B to link the second seed beam to MOPA 1620B and reflect laser beam 1670B to deactivate laser beam 1670B, thereby stopping providing laser beam 1670B; ,
is configured to provide fast and effective modulation of the output laser beam 1670B according to a method comprising:

In some embodiments, λ1 and λ2 are selected such that their difference (λ2≠λ1) allows beam activation/deactivation according to the embodiments and their selected features described above. be done.

Reference is now made to FIG. 7A. FIG. 7A shows a laser system 1700A configured to provide and condition a laser beam 1770 (more specifically a high power laser beam), according to some embodiments of the invention.
This laser system 1700A
at least one seed laser device 1710;
an optical polarization combiner (OPC) 1717 configured to receive the seed laser beam of the seed laser device and adjust the polarization direction thereof, wherein the adjustment of the polarization direction provides the seed beam with at least two polarization components; and one of the polarization components has a predetermined polarization direction (P1);
a coherent beam combining (CBC) system 1701 configured to receive a polarization modulated seed laser beam 1718 and provide an amplified laser beam 1772;
Amplified laser beam 1772 is received and only beams with a given polarization direction (P1) are transmitted to the output of laser system 1700A, and beams with other polarization directions are reflected, thereby selectively diverting laser beam 1770. a polarizing beam splitter (PBS) 1790 configured to provide a
Output laser beam 1770 is provided by CBC system 1701 .

In some embodiments of the invention, the components of the CBC system can come in a variety of designs and configurations, some of which are known in the art, non-limiting examples of which are: A CBC system 1101 as shown in FIG. 1, or another non-limiting example is a CBC system 1701 as shown in FIG. 7A.
The CBC system 1701 shown in FIG. 7A includes:
a plurality of phase adjusters 1750;
at least one control circuit 1760;
A plurality of phase adjusters 1750 include a polarization adjusted seed laser beam 1718, a plurality of optical amplifiers 1720, at least one configured to be optically connected, directly or indirectly, to beam splitter 1730 and, optionally, at least one beam combiner 1740;
At least one control circuit 1760 is configured to monitor beam interference at CBC point 1771 and control at least one of the plurality of phase adjusters accordingly.

In some embodiments, laser system 1700A includes:
To activate the laser beam 1770, the OPC 1717 is controlled to direct the beam component with the predetermined polarization direction (P1) to an intensity greater than 50% (preferably about 100%) of the total intensity of the seed laser beam. (I1), thereby providing an output laser beam 1770;
To deactivate laser beam 1770, OPC 1717 is controlled to reduce the beam component with a predetermined polarization direction (P1) to an intensity (preferably about 0%) of the total intensity of the seed laser beam ( I1), thereby ceasing to provide the output laser beam 1770;
is configured to provide fast and effective modulation of the output laser beam 1770 according to a method comprising:

In some embodiments, the method includes controlling the OPC 1717 to provide a beam component having a predetermined polarization direction (P1) with an intensity (I1) equal to a predetermined percentage of the total seed laser beam intensity. further comprising adjusting the laser beam by .

In some embodiments, the method further includes controlling phase adjuster 1750 by control circuit 1760 to allow constructive interference at CBC point 1771 . In some embodiments, the above step of controlling the phase adjuster is performed only during the above step of activating the laser beam and not during the above step of deactivating the laser beam.

In some embodiments, the above step of controlling phase adjuster 1650 to provide constructive beam interference includes adjusting the phase adjuster to provide constructive beam interference at maximum intensity.

In some embodiments, constructive interference is considered when the laser intensity is greater than about 50% of the maximum intensity. Preferably, constructive interference is considered when the laser intensity is about 100% of the maximum intensity. In some embodiments, destructive interference is considered when the laser intensity is below the maximum intensity. Preferably, constructive interference is considered when the laser intensity is about 0% of the maximum intensity.

In some embodiments, as shown in FIGS. 8A and 8B,
The optical polarization combiner (OPC) 1717 is
A beam splitting assembly 1820 for receiving an input beam having a first polarization direction (P1) and for receiving a first beam (B1(I1, P1)) and a second beam (B2(I2, P1)) having a first polarization direction (P1) and a second intensity (I2), wherein the first intensity and the second beam the beam splitting assembly 1820, whose sum with the intensity of 2 (I1+I2) is equal to the intensity of the input seed beam;
a polarization converter 1830 for receiving one of the first beam B1 and the second beam B2 output from the beam splitting assembly 1820 and converting the polarization thereof from S to P or P to S; B1 (I1, P1) and B2 (I2, P2), P1 ≠ P2 if configured (e.g., converting the polarization of B2 (as shown in FIGS. 8A and 8B); or as another example, If converting the polarization of B1 (not shown), B1 (I1, P2) and B2 (I2, P1)), the polarization converter 1830;
A polarizing beam splitter (PBS) 840A (shown in FIG. 8A) that separates a first output beam (B1(I1,P1)) and a polarization-converted second output beam (B2(I2,P2)); and combine (superimpose) them to produce a third beam, wherein Receive a first output beam (B1(I1,P1)) and a second polarization-converted output beam (B2(I2,P2)) and combine (superimpose) them into two output beams. and the coupler 1840B configured to split and provide only one of the two split output beams as an input to the CBC system 1701 . In some embodiments, other output beams are used by other systems.

In some embodiments,
Beam splitting assembly 1820 includes:
a beam splitter 1821 configured to receive an input beam and split the input beam into two output beams (in some embodiments, the intensity relationship between the two output beams is constant);
a phase adjuster 18222 configured to adjust the phase of one of the two output beams;
Receive two output beams (after adjusting the phase of one of the two output beams) and provide their interference at two positions 1823A, 1823B, thereby producing a first output beam (B1(I1,P1 ))) and a second output beam (B2(I2, P1));
Electronic controller 1826 monitors one of two interference locations 1823A by TAP 1824 and diode 1825 and controls phase adjuster 1822 accordingly to constructively or the electronic controller 1826 configured to enable destructive beam interference and to provide destructive or constructive beam interference at the unmonitored interference location 1823B;
thereby determining a first intensity (I1);
Control of OPC 1717 includes controlling phase adjuster 1822 (via electronic controller 1826).

In some embodiments, control of OPC 1717 is provided by at least one control circuit 1760 of CBC system 1701 . In other embodiments, control of optical switch 1717 is provided by higher level control circuitry 1761 configured to control both optical switch 1717 and at least one control circuitry 1760 of CBC system 1701 .

Reference is now made to FIG. 7B. FIG. 7B shows a laser system 1700B configured to provide and condition a laser beam 1770B, according to some embodiments of the invention.
This laser system 1700B
a seed laser device 710B;
an optical polarization combiner (OPC) 1717 configured to receive the seed laser beam of the seed laser device and adjust its polarization direction (adjusting the polarization direction includes providing at least two polarization components to the seed beam); , one of the polarization components has a predetermined polarization direction (P1)),
a master oscillator power amplifier (MOPA) 1720B configured to receive the polarization modulated seed beam and provide an amplified laser beam 1772B;
Amplified laser beam 1772B is received and only beam components with a given polarization direction (P1) are transmitted to the output of laser system 1700B and beam components with other polarization directions are reflected, thereby output laser beam 1770B a polarizing beam splitter (PBS) 1790B configured to selectively provide a .

The laser system 1700B is
To activate laser beam 1770B, provide a beam component having a predetermined polarization direction (P1) with an intensity (I1) greater than 50% (preferably about 100%) of the total intensity of the beam. controlling OPC 1717 thereby providing laser beam 1770B;
providing a beam component having a predetermined polarization direction (P1) at an intensity (I1) of 50% or less (preferably about 0%) of the total intensity of the seed laser beam to deactivate the laser beam 1770B; thereby ceasing to provide output laser beam 1770B;
is configured to provide fast and effective modulation of the output laser beam 1770B according to a method comprising:

All embodiments of the present invention include a laser tuning method and/or that keeps the seed laser and CBC system (and its various components) active during both tuning states (beam "on"/beam "off"). It should be noted that a system is provided, thereby preventing damage that can be caused by "shutting down" or "blocking" the seed beam as described in the background section.

In some embodiments of the present invention, the laser conditioning means and/or systems 1200, 1300, 1400, 1500, 1600A, 1600B, 1600C, 1700A, 1700B described above are controlled by their control circuits to limit switching elements. used for quasi-continuous wave (QCW) operation of laser means at very high frequencies up to 10 GHz (e.g. 10 MHz, 100 MHz, 1 GHz, 100 GHz, 100 GHz and any combination thereof) depending on can do. In some embodiments of the present invention, the laser conditioning means and/or systems 1200, 1300, 1400, 1500, 1600A, 1600B, 1600C, 1700A, 1700B described above are controlled by their control circuits to % range (e.g. 1%, 5%, 10%, 25%, 50%, 75%, 95%, 99% and any combination thereof) of the quasi-continuous laser means. It can be used for wave (QCW) operation.

In some embodiments of the invention, at least some of the above methods of using the above systems 1200, 1300, 1400, 1500, 1600A, 1600B, 1600C, 1700A, 1700B provide for more flexible operation of the laser beam. Therefore, they can be combined into one laser system.

Hybrid fiber-coupled diode-pumped laser module

In some embodiments, the present invention provides a method and apparatus configured to provide an optical signal amplifier, and more particularly a hybrid fiber-coupled diode pump laser configured to be coupled to an optical fiber. It relates to a module (abbreviated hybrid pump module). Those skilled in the art will appreciate that the term "hybrid" refers to a combination of a pump and a signal in some embodiments.

Those skilled in the art will appreciate that a fiber amplification system absorbs and combines energy from multiple multimode pumps and typically a single single mode seed device, and amplifies it to output a high power single mode beam. You will understand that the

A generic or typical model/design of a fiber amplification system is shown in FIG. The fiber amplification system 2100 includes a seed laser device 2110, an amplifier 2120 connected to the seed laser device 2110 by an optical fiber (connection by the optical fiber is indicated by a line, fusion points are indicated by x), an isolator 2130, a tap element 2140, It includes a monitor 2141 and a mode field adapter (MFA) 2150, all of which are used as inputs to a multimode combiner (MMMC) 2170. A multimode combiner (MMMC) 2170 is configured to combine the optical fibers of the six pump modules 2160, along with one optical fiber extending from the seed device, into the active fiber 2180. Active fiber 2180 is configured to receive an input signal and produce an output signal having a higher optical power. As shown, active fiber 2180 is connected at one end to the MMC (as described above) and at its other end to pump dump 2190, configured to dump residual pump power and scattered signals into the cladding. ing. The output of the system is typically through an output fiber with an end cap 2191 . As shown, the use of optical fibers to transmit light beams requires multiple splice points 2192 symbolically indicated by "x".

Those skilled in the art will appreciate that the above "fusion point" is also known as a fusion bond. Those skilled in the art will understand that fusion splicing is the act of joining the ends of two optical fibers using heat. The purpose is to ensure that light passing through the optical fiber is not scattered or reflected by the fusion splice, and that the fusion splice and the area around it have approximately the same intensity as the original optical fiber. It is the fusing of two optical fibers together. Before the fusion spliced optical fiber is removed from the fusion splicer, a proof test is performed to ensure that the fusion splice of the optical fiber has sufficient strength for handling, packaging, and long-term use. is done. Bare fiber optic areas are protected by recoating or splice protectors. Accordingly, there is a need for a fiber amplification system that can reduce the number of splices, thereby reducing energy loss and manufacturing costs.

Those skilled in the art will understand that the term "multimode combiner (MMC)" is used to combine multiple fibers such that light from the pump module enters the cladding and light from the seed enters the core, making it compatible with fiber amplifiers. It will be understood to refer to an optical element configured to couple to a single fiber (in the example of FIG. 9, six pump-connected fibers to a single seed-connected fiber). MMCs are expensive because they are complex devices (eg, they require special features to dissipate heat).

Those skilled in the art will recognize that the term "fiber amplifier" or "active fiber amplifier" is used in some embodiments to refer to multiple pump modules and seed-related modules (e.g., in FIG. 9, six multimode beams and one It will be understood to refer to a doped fiber that receives power from a single mode beam) and outputs a single mode beam with enhancement (due to the single mode seed). The overall diameter can be about 400 microns and the core diameter can be about 20 microns. Light from the pump module enters the cladding and light from the seed enters the core. For example, fiber amplifiers are based on "active" fibers having fiber cores doped with laser active ions such as Er3+, Nd3+, or Yb3+. A fiber coupler is typically used to introduce some "pump light" in addition to the input signal light. This pump light is absorbed by the laser active ions and transitions to an excited electronic state, thereby allowing amplification of other wavelengths of light by stimulated emission.

Those skilled in the art will understand that the term "pump dump" is, in some embodiments of the present invention, a beam dump, which is a device designed to absorb or deflect residual unabsorbed pump power or scattered signals in the cladding. will be understood to refer to In the example of FIG. 9, the residual emission in the cladding of the active fiber is absorbed.

Those skilled in the art will appreciate that the term "isolator" refers, in some embodiments of the invention, to an optical element configured to allow transmission of light in only one direction. .

Those skilled in the art will appreciate that the term "pump module" refers to a module having diodes that provide a multimode beam in some embodiments of the invention. Those skilled in the art will understand that the term "broad area laser (BAL) diode" refers to a diode that provides a multimode beam with an elliptical cross-sectional shape. A BAL (also called broad stripe diode, broad emitter laser diode, single emitter laser diode, high brightness diode laser) is an edge-emitting laser diode in which the emitting area of the front facet has the shape of a broad stripe.

Those skilled in the art will appreciate that the term "single-mode", in some embodiments of the present invention, refers to a light beam that has only one transverse mode excited.

Those skilled in the art will appreciate that the term "polarizer beam combiner" refers, in some embodiments of the present invention, to an optical element configured to combine two signals with perpendicular polarizations together. would do.

Those skilled in the art will appreciate that the term "volume Bragg grating" (VBG) is used in some embodiments of the present invention to reflect an incident beam at an angle relative to the wavelength of the incident beam. It will be understood to refer to an optical means comprising a diffraction grating within a glass block configured to. A common application of volume Bragg gratings is for wavelength stabilization of lasers, often used for wavelength stabilization of laser diodes.

Those skilled in the art will appreciate that the term "end cap" refers to optical means configured to magnify the cross-section of a beam in some embodiments of the invention. Fiber end caps are made by fusion bonding or laser fusing a short length of material to the end face of the fiber. Fiber end caps have many applications including the fabrication of collimators to reduce the power density at the air/silica interface and to allow expansion of high power fiber laser beams to protect structured fibers from environmental intrusions. is needed in

Those skilled in the art will understand that the term "phase adjuster" refers to an optical adjuster used to control the optical phase of a laser beam. Commonly used types of phase adjusters are Pockels cell-based electro-optical modulators, lithium niobate (LiNbO3) electro-optical modulators, liquid crystal modulators, etc., but e.g. It is also possible to use refractive index changes or length changes, or to induce changes in optical fiber length by drawing. Various types of phase adjusters are used in the field of integrated optics to propagate modulated light through waveguides.

Those skilled in the art will recognize that the term "beam splitter" is used in some embodiments of the present invention to divide an incident light beam (e.g., a laser beam) with or without the same optical power. It will be understood to refer to an optical device configured to split into two or more beams.
In some embodiments, the beam splitter can include at least one of dielectric mirrors, cubes, fiber optic splitters, planar lightwave circuit (PLC) splitters, diffraction gratings, and multimode interference (MMI). .
A dielectric mirror can be any partially reflective mirror that can be used to split a light beam. In laser technology, dielectric mirrors are often used for this purpose. The angle of incidence determines the angular separation of the output beams, which affects the properties of the beamsplitter, eg, 45 degrees (this value is often convenient, but other values are possible). A wide range of power division ratios can be achieved with various designs of dielectric coatings.
The cube splits the beam at its interfaces. Cubes are often made by gluing two triangular glass prisms together with clear resin or cement. The thickness of the layer can be used to adjust the power split ratio for a given wavelength.
A fiber optic splitter is a type of fiber optic coupler that is used as a fiber optic beam splitter. Such devices may be made by fusion splicing optical fibers and may have more than one output port. As with bulk devices, the splitting ratio may or may not be strongly dependent on the wavelength and polarization of the input.
A PLC is either an integrated optical circuit (IC) or an optical circuit board made with optical waveguides to route photons.
A diffraction grating is an optical element having a repeating structure that splits and diffracts light into multiple beams traveling in different directions. The direction of travel of these beams depends on the grating spacing and the wavelength of the light. In some embodiments, diffraction gratings can also be used as beam combiners.
Multimode interference (MMI) is an optical waveguide with a spatially non-uniform structure for guiding light, i.e. limiting the spatial region in which light propagates. MMIs can be used, for example, for splitting and combining light beams in integrated optical interferometers.

Those skilled in the art will appreciate that the term "fiber coupler" or "coupler" refers to an optical fiber device having one or more input fibers and one or more output fibers. Light from an input fiber can appear at one or more outputs, with an output distribution potentially dependent on wavelength and polarization.

Those skilled in the art will recognize that the term "tap" or "tap element" is used in some embodiments of the present invention for combined power ratios of 50:50, 75:25, 90:10, or 99:1. will be understood to refer to a coupler configured to Fiber tapping can use a network tap method that extracts the signal from the optical fiber without breaking the connection. Tapping an optical fiber allows part of the signal being transmitted in the core of the fiber to be diverted to another fiber or detector.

Those skilled in the art will understand that the term "optical amplifier" refers to a device that transmits an input signal and produces an output signal having a higher optical power. In some embodiments, the input and output are laser beams propagated in free space or in fibers. Amplification takes place within a so-called gain medium, which must be "pumped" (ie supplied with energy) from an external source. In some embodiments, the optical amplifier is optically, chemically, or electrically pumped.

Those skilled in the art will appreciate that the term "dichroic mirror" refers to a mirror that has significantly different reflective or transmissive properties at two different wavelengths.

Those skilled in the art will appreciate that the term "seed laser" in some embodiments of the present invention refers to the output of a laser that is injected into an amplifier or another laser. Typical types of seed lasers are miniature laser diodes (single-frequency or gain-switched), short-cavity fiber lasers, and miniature solid-state lasers such as non-planar ring oscillators (NPROs).

Reference is now made to FIGS. 10A-10D. 10A-10D schematically illustrate a hybrid pump module configured to be coupled to an optical fiber 2240. FIG. In some embodiments, the optical fiber is a doped (active) fiber or a passive fiber (data format transmissive). The optical fiber includes core 2241 and at least one cladding 2242 . As shown in FIGS. 10A-10D,
The pump module 2200 is
at least one focusing lens 2230 positioned in the free space optical path of the optical fiber 2240;
a plurality of diode modules 2210, each configured to output a multimode beam through an optical lens, disposed in the free space optical path of the cladding 2242 of the optical fiber;
at least one core-associated module 2220 positioned in the free-space optical path of the core 2241 of the optical fiber;
Core related module 2220 includes:
(a) the ability to output a single-mode beam through an optical lens into the core 2241 of an optical fiber;
(b) receiving the beam from the core of the optical fiber 2241 through a focusing lens and coupling the received beam to the output optical fiber 2411 (FIG. 12);
(c) the ability to receive a beam from the core 2241 of the optical fiber through the focusing lens and reflect the received beam back to the core 2241 through the focusing lens;
(d) receive the beam from the core 2241 of the optical fiber through the focusing lens, reflect a portion of the received beam back through the focusing lens back to the core, and direct another portion of the received beam to the output optical fiber; 2610 (FIG. 14).

In some embodiments, the term "single-mode beam" refers to a beam consisting of one or several beam modes ranging from 1-10 modes.

In some embodiments, multiple diode modules 2210 are placed in the free space optical path of the cladding 2242 of the optical fiber. In some embodiments, this optical path does not include an optical fiber for the optical path. In some embodiments, a portion of the diode module 2210 is also placed in the free space optical path of the core 2241 of the optical fiber.

In some embodiments, core-associated module 2220 is placed only in the free-space optical path of core 2241 of the optical fiber. This means that no light is coupled into the cladding 2242 of the optical fiber 2240 . In some embodiments, this optical path does not include an optical fiber for the optical path.

In some embodiments, the hybrid pump module 2200 further comprises a volume Bragg grating (VBG) 2250 configured to narrow and lock the wavelength of the diode's beam to a narrow predetermined range of wavelengths. In some embodiments, a typical VGB is a 976 wavelength-locked module that is perfectly matched with high absorption, narrow linewidth yttrium boride (Yb) ions. In some embodiments, VGB 2250 is positioned between focusing lens 2230 and optical fiber 2240, as shown in FIG. 10D.

In some embodiments, a plurality of diode modules 2210 and core-associated modules 2220 are arranged in at least one row 2281 such that their output beams are parallel to each other row by row. 10A, 10B, and 10C are isometric, top and front views of a system in which multiple diode modules 2210 (eight diode modules in this example) and core-associated modules 2220 are arranged in line. Figure shows. FIG. 10D is an isometric view showing a system with multiple diode modules 2210 (17 diode modules in this example) and core-associated modules 2220 arranged in two columns 2281 , 2282 .

In some embodiments, as shown in FIG. 10D, when arranged in two or more rows 2181, 2182, the pump modules:
at least one polarizer beam combiner 2260 positioned in the optical path of the first beam train 2281;
One or more fold mirrors 2282 A for each additional beam column, each configured to reflect and redirect the parallel beams of its corresponding column toward polarizer beam combiner 2260 . and a mirror 2282A.

In some embodiments, as shown in FIGS. 10A and 10B,
Each of the diode modules 2210
a broadband laser (BAL) 2211 configured to output a multimode beam;
a folding mirror 2212 associated with a BAL 2211 configured to have an optical path between its associated BAL 2211 and the cladding 2242 of the optical fiber (via a focusing lens 2230);
optionally, at least one lens 2213, 2214 disposed between the BAL 2211 and its associated folding mirror 2212 and configured to shape the beam of the BAL 2211.

Reference is now made to FIGS. 11A-11C. 11A-11C schematically illustrate a hybrid pump module 2300 that includes at least some features and elements similar to the hybrid pump module 2200 shown in FIGS. 10A-10D. In some embodiments, the core-associated module is a seed-associated module 2301 configured to output a single-mode beam through an optical lens toward the core of the optical fiber.
This seed related module 2301
at least one seed input 2311 configured to be coupled to seed laser apparatus 2702 (FIG. 15) via optical fiber 2310;
a folding mirror 2312 associated with the seed input placed in the optical path between the seed input and the core 2241 of the optical fiber through the focusing lens 2230;
optionally, at least one lens 2313 disposed between the seed input and its associated folding mirror 2312 and configured to adjust the shape of the seed beam.

In some embodiments,
Seed related module 2301
11A, placed between the seed input 2311 and the optical lens 2313 or folding mirror 2312 to sample and monitor the seed beam to warn of backward beam transmission (transmission back to seed input 2311). Configured tap (not shown) or partial mirror 2305 and monitor 2306,
11B, a beam amplifier 2315 positioned between the seed input 2311 and the optical lens 2313 or folding mirror 2312 and configured to amplify the seed beam; and
11C, an isolator 2316 positioned between the seed input 2311 and the optical lens 2313 or folding mirror 2312 and configured to allow transmission of light in only one direction;
further comprising at least one of

Reference is now made to FIG. Figure 12 schematically illustrates a hybrid pump module 2400 that includes at least some features and elements similar to the hybrid pump module 2200 shown in Figures 10A-10D. In some embodiments, the core-related module is an output module 2401 configured to receive a beam from the core of the optical fiber and couple the received beam to an output optical fiber 2411 via a focusing lens.
This output module 2401 is
an output fiber 2411, optionally including an end cap element 4209;
a folding mirror 2412 associated with the output fiber 2411 in the optical path between the optical fiber core 2241 and the output fiber 2411;
optionally, at least one lens 2413 disposed between the output fiber 2411 and its associated folding mirror 2409 and configured to adjust the shape of the received core beam;
optimally including a pump dump (not shown);

In some embodiments, output module 2400 includes a tap (not shown) or partial mirror positioned between output fiber 2411 and optical lens 2413 or folding mirror 2412 and configured to sample the seed beam. 2405 and a monitor 2406 configured to monitor and warn of beam back transmission (transmission back to folding mirror 2412).

Reference is now made to FIG. FIG. 13 schematically illustrates a hybrid pump module 2500 that includes at least some features and elements similar to hybrid pump module 2200 shown in FIGS. 10A-10D. In some embodiments, the core-associated module is configured to receive a beam from the core 2241 of the optical fiber through the focusing lens and reflect the received beam back to the core 2241 through the focusing lens. A high reflectance (HR) module 2501 .
This high reflectance (HR) module 2501
a high reflectance (HR) mirror 2511;
a folding mirror 2512 associated with the HR mirror 2511 in the optical path between the optical fiber core 2241 and the HR mirror;
optionally, at least one lens 2513 disposed between the HR mirror 2511 and its associated fold mirror 2512 and configured to adjust the shape of its associated beam.

In some embodiments, (HR) module 2501 is configured to reflect the received beam back and forth in the form of a fiber resonator.

In some embodiments, HR module 2501 is positioned between HR mirror 2511 and its associated folding mirror 2512 and is configured to adjust the amplitude, phase, polarization, or any combination thereof of the reflected beam. It further includes an intracavity adjuster 2510 that is designed for use in a single cavity. In some embodiments, the intracavity adjuster comprises an acousto-optic adjuster or an electro-optic adjuster. In some embodiments, the intracavity modulator enables pulsed laser behavior.

Reference is now made to FIG. Figure 14 schematically illustrates a hybrid pump module 2600 that includes at least some features and elements similar to the hybrid pump module 2200 shown in Figures 10A-10D. In some embodiments, the core-related module is a partial reflection (PR) module 2601.
This partial reflection (PR) module 2601
an output fiber 2610, optionally including an end cap 2609;
a partially reflective (PR) mirror 2611 positioned in the optical path of the output fiber 2610;
a folding mirror 2612 associated with the PR mirror 2611 in the optical path between the optical fiber core 241 and the PR mirror 2611;
optionally, at least one lens 2613 disposed between the PR mirror 2611 and its associated fold mirror 2612 and configured to adjust the shape of its associated beam.

In some embodiments, the assembly of hybrid pump modules 2200, 2300, 2400, 2500, 2600 can be opto-mechanical by measuring beam paths and adjusting component positions and/or orientations as described above. are configured to be systematically aligned. In some embodiments, this adjustment is provided by a jig vacuum catcher. In some embodiments, the regulated component is any one of the core modules, any one of the diode modules, any one of the seed devices, any one of the BALs. 1, any one of folding mirrors, any one of lenses, any one of beam amplifiers, any one of tap or partial mirrors and monitors, any one of isolators Any one of the HR mirrors, any one of the PR mirrors, any one of the seed inputs, a focusing lens, and at least one selected from the VGB.

In some embodiments, at least some of the lenses 2213, 2214, 2313, 2413, 2513, 2613 configured to cross-section the beams include a fast access collimator (FAC) 2213 and a slow access collimator ( SAC) 2214.

In some embodiments, at least a portion of the folding mirrors 2212, 2312, 2412, 2512, 2612 redirect a portion of the reflected beam for further monitoring purposes (eg, as shown at 2399 in FIG. 11). It is configured to tap (pass).

FIG. 15 schematically illustrates a fiber amplification system 2700. FIG. In some embodiments of the invention,
This fiber amplification system 2700 includes:
an active optical fiber 2740 including a core and at least one cladding;
The embodiment described above includes a hybrid pump module 2300 including a seed-related module 2301 coupled to the first end 2744 of the optical fiber.

As shown in FIG. 15, fiber amplification system 2700 is configured to receive a seed laser beam from seed laser device 2702 and amplify it into a high power single mode laser beam.

In some embodiments, the fiber amplification system 2700 further comprises a hybrid pump module 2400 including an output module 2401 coupled to the second end 2745 of the optical fiber.
Those skilled in the art will appreciate that hybrid pump module 2400 operates as a counter-pump module configured to increase beam amplification in active optical fiber 2745 .

In some embodiments, the fiber amplification system 2700 includes at least one selected from a pump dump 2703 and an output fiber 2411 having an end cap element 2704 coupled to a second end 2745 of the active optical fiber 2740. Further includes one.

Those skilled in the art will appreciate that, according to various embodiments such as those described above, the fiber amplification system 2700 greatly reduces the number of fusion splices required while allowing independence from the number of diode modules. You will understand what you can do. For example, the prior art system 2100 shown in FIG. 9 includes six diodes and requires at least nine fusion junctions. The system 2700 of the present invention includes at least eight (and possibly more) diode modules, yet only requires two fusion joints.

Reference is now made to FIGS. 16A and 16B. Figures 16A and 16B schematically illustrate a fiber laser system 2800, according to some embodiments of the invention.
This fiber laser system 2800 is
an optical fiber 2840 including a core and at least one cladding;
a hybrid pump module 2500 including a high reflectance (HR) module 2501 coupled to a first end 2844 of an optical fiber;
A fiber Bragg grating (FBG) 2804 (shown in FIG. 16B) or a partial reflection (PR) module 2601 (shown in FIG. 16A) coupled to the second end 2845 of the optical fiber. and a hybrid pump module 2600 .

Those skilled in the art will appreciate that hybrid pump module 2600 operates as a counter-pump module configured to increase beam amplification in active optical fiber 2840 .

In some embodiments, fiber laser system 2800 further includes at least one of pump dump 2803 and an output fiber including end cap element 2804 .

Enhanced frequency conversion using a weak high-frequency seed beam collinearly generated within the primary beam

Some embodiments of the present invention relate to frequency conversion of high average power laser beams in nonlinear crystals (NLCs). In some embodiments, in the example of frequency doubling light with a wavelength of 1064 nm, the term "high average power" refers to power greater than 300 W from a continuous laser, and in low absorption LBO, "high green light output" is greater than 100W.

In some embodiments, the present invention provides a fundamental frequency input beam and a frequency converted output beam that can occur at the beginning of a nonlinear crystal (NLC) single or multiple output frequency multiplier (PFD) chain. provides a means for correcting the deleterious phase mismatch (MP) between

Note that the present application discloses in some embodiments "nonlinear crystal", abbreviated "NLC", or "crystal", these terms being used interchangeably. The present application discloses, in some embodiments, an "output frequency multiplier", abbreviated "PFD", or "multiplier". Note that these terms are used interchangeably. The present application discloses, in some embodiments, a “non-linear crystal output frequency multiplier”, abbreviated “PFD-NLC”, or “NLC multiplier”, or “crystal multiplier”. Note that these terms are used interchangeably. The present application discloses, in some embodiments, "second harmonics", or "harmonics" for short. Note that these terms are used interchangeably.

In some embodiments, two factors are controlled for efficient frequency conversion: the temperature of the interaction region of the crystal and the relative phase between the fundamental beam and the output harmonic beam of the NLC. be done.

In the prior art, only near-optimal crystal parameters in the harmonic conversion regime were maintained by an oven associated with the first NLC multiplier, which is located at the entrance of the first NLC multiplier (first We did not control the phase mismatch that builds up as the beam propagates from (where the harmonic photons of ) originated to the primary harmonic conversion region of that first NLC multiplier. This resulted in poor frequency conversion of high power. The reason is that the uniform temperature oven (UTO) has only one variable parameter (oven temperature) and the mismatch phase (MP) of the beam near the input face of the oven is determined by the local temperature at that location. It is for In some embodiments, the present invention provides any required position between beams in front of the first NLC multiplier such that the beams are optimized to propagate into the harmonic conversion domain. Provide a means of imposing a difference.

An approach reported in the literature is the use of two PFD-NLCs with an intermediate phase mismatch compensator (PMC). PMCs are optical elements that exhibit chromatic dispersion and/or polarization dependent refractive index. This dispersion can be an intrinsic property of the material or it can be imposed by an external field, for example an electric field applied to an electro-optic material such as a Pockels cell.

The advantage of this in-line, crystal-PMC-crystal approach is that the dispersive element only acts to generate a controllable phase difference between co-propagating beams of two wavelengths, and There is no need to achieve interferometric (sub-wavelength) optical path length control. This greatly reduces sensitivity and stability requirements.

The key points about the prior art of phase mismatch correction are (i)-(v) below.
(i) Each NLC is configured to achieve maximum frequency conversion. That is, each NLC functions as a PFD. The lowest absorption grade is sought for each type of crystal used.
(ii) The PMC corrects the thermally induced mismatch phase (TMP) of the first crystal only after exiting the first crystal.
(iii) The PMC can correct the TMP of the second double crystal multiplier along with temperature and/or angle adjustments.
(iv) to date, other than for temperature or angle adjustment of the first PFD crystal, means for compensating the TMP in the first crystal placed in a uniform temperature oven (UTO), or There was no means to maintain the conditions for optimal harmonic conversion in the dominant harmonic conversion region (the focal region when using a focusing lens).
(v) A more complex gradient temperature oven (GTO) can eliminate MP generation in a single oven. However, in GTO, the input and output temperatures of the oven must be controlled if a linear gradient is desired, and if the temperature rise due to light absorption varies along the length of the crystal (crystal ), it is necessary to control the temperature at multiple points along the axis of the oven.

In some embodiments, the invention presented herein provides a means for overcoming the limitation described in (iv), a means for compensating MP in the first PFD-NLC, i.e. A means for improving the multiplication efficiency in the first (and subsequent) PFDs.

In some embodiments of the present invention, as shown in FIG. 17A, the above improvement is achieved in a “seeder” NLC 3100 placed in the optical path of the high-power fundamental beam 3101 before the first PFD-NLC 3200. It is provided by generating a low power second harmonic seed beam. The phase difference between the fundamental beam 3101 and the harmonic beam 3202 from seeder NLC 3100 is controlled by the addition of PMC 3501 . In some embodiments, the seeder NLC 3100 is placed in a temperature controlled oven 3701, as shown in FIG. 17B. In some embodiments, a PMC 3502 positioned after the seeder crystal 3100 is provided with a feedback control system 3602 . A feedback control system 3602 is configured to sample the harmonic light 3202 after the first PFD-NLC 3200 and control the PMC to maximize the harmonic light 3202 .

It is emphasized that the seeder crystal 3100 need only produce a low power harmonic beam 3102 whose phase is controllable with respect to the fundamental beam 3101 . Therefore, there is no need to focus the fundamental beam to a small spot in the seeder crystal 3100, and the seeder crystal has approximately the same length (Ls) used for the first NLC multiplier 3200. You don't have to have

Optical absorption at high power produces lateral and axial temperature variations that affect harmonic conversion. Therefore, at all positions along the propagation axis (from the front surface through any focal point to the back surface) the temperature increases with increasing laser power. Therefore, the temperature of the oven must be lowered as the laser power increases.

In some embodiments, in all cases using a uniform temperature oven (UTO), the temperature along the optical axis is due to changes in absorption (green light absorption higher than IR light absorption). , and if a focusing lens is used to increase the laser intensity, the cooling will be higher towards the rear half of the crystal, since it will vary depending on the laser beam radius. In the prior art scenario, there is no independent control of the initial phase matching between the fundamental and harmonic beams in the first PFD-NLC. The only observable parameter is the output harmonic power, which is affected by what happens along the entire length of the crystal. The prior art scenario is to maximize the amount of harmonic light produced by varying the temperature of the oven. In the case of focused beam phase matching, the main concern is maintaining the correct temperature in the focal region. Varying the temperature to optimize the harmonic conversion in the focal region means that there is no optimum temperature at the beginning of the crystal. The resulting MP degrades the harmonic conversion. The present invention provides the following improvements.

In some embodiments, the oven temperature can be readjusted to obtain phase matching in the focal region, while in the UTO, the MP accumulated in the front-to-middle portion of the first PFD-NLC is corrected. Can not do it.

In some embodiments, by adding a second harmonic seed beam 3102 that is weaker than the high power fundamental beam 3101 before the first PFD-NLC 3200, the control of phase matching in the focal region is independent. Thus, it is possible to adjust the input phase difference before the first PFD-NLC.

According to embodiments of the present invention, a "short" nonlinear crystal (seeder crystal) 3100 is provided in front of the NLC 3200 of the first long PFD. The seeder crystal 3100 is configured to produce a weaker second harmonic beam than the stronger fundamental beam, which is of controllable phase.

In some embodiments, a PMC 3501 is provided after the seeder NLC 3100 to adjust the IR-green MP. The IR-green MP is adjusted so that the MP of the seeder NLC plus the MP of the first PFD in the first half of the first PFD-NLC equals zero.
ΣMP = MP _seeder + MP _{1/2 PFD} = 0

Note that the MP accumulated in the front half of the PFD crystal is more important than the MP accumulated in the second half. This is because the MP up to the focus strongly influences the multiplication of the focal area. The MP accumulated after the focal region does not strongly degrade the crystal's multiplication since its intensity is already reduced. Additionally, the second half of this MP can be modified by the next PMC.

Note that if heat is generated by NLC absorption, the temperature will deviate from that required for phase matching, especially non-critical phase matching (NCPM).
As a negative effect,
reduction in temperature, angle, spectral bandwidth (which is most important in the focal region where most of the multiplication occurs); and
that phase mismatch occurs as the beam propagates through the crystal (even in weakly multiplied regions; this phase mismatch can reduce later multiplication efficiency and cause inverse conversion; accumulation of MP is most important between the plane of incidence and the edge of the focal region),
are mentioned.

In some embodiments, uniform oven temperature readjustment techniques are provided to mitigate some of the thermal effects.

In some embodiments, adjusting the oven temperature has only one effect, either to achieve T=T _{phase matching} in the focal region or to achieve ΣMP=0 up to the focal region of the NLC. can be corrected.

In some embodiments, the addition of seeders NLC and PMC allows the input phase to be set as a conjugate to the phase mismatch of the crystal.
Δφ _seeder = (-) MP _PFD
That is, it is independent of the temperature of the focal region of the PFD-NLC.

In some embodiments, a PMC may not be required. The seeder crystal itself can create the phase mismatch required for optimum multiplication in the output crystal multiplier. The source of this misalignment may be provided by a controlled level of heating of the seeder crystal during passage of the IR beam, or an intentional shift caused by an operator-imposed change in oven temperature. Recall, however, that changing the temperature of the oven slows down the reaction significantly more than rotating the PMC or applying a voltage to the electro-optical PMC device.

In some embodiments, the PMC produces a desired phase difference or a predetermined phase difference no matter what phase difference (between the fundamental and harmonic beams) occurs in the seeder crystal. can do. In some embodiments, the PMC can be adjusted much faster than changing the oven temperature. In some embodiments, the PMC allows the output of the seeder crystal to remain fixed constant as the phase difference is adjusted.

In some embodiments, any phase mismatch that occurs within the PFD-NLC can be mitigated through the use of seeder NLCs to mitigate the MP generated due to changes in laser wavelength and/or oven temperature. with a conjugate mismatch to

In some embodiments, the techniques described above can be applied to any periodically poled crystal with a constant poling period.

Reference is now made to FIGS. 17A-17C. 17A-17C show a weak second harmonic seed beam 3102 configured to control its phase relative to a high power input beam (fundamental beam) 3101, according to various embodiments of the present invention. Several setups 3100 for the device 3000 are shown. In some embodiments, after generating the second harmonic seed beam 3102 and adjusting the phase offset, the beam is propagated to a power frequency doubling (PFD) crystal 3200 . In the example shown, one long wavelength beam is frequency doubled. An achromatic optic 3402 (achromatic lens or multi-wavelength mirror) can be used to focus both beams 3102, 3103 to the same point on the first PFD crystal 3200, thereby increasing the intensity and thus Frequency conversion can be enhanced.

In some embodiments, frequency doubling is efficient when phase matching occurs.

In some embodiments, the input waves 3102, 3103 propagate at exactly the same velocity through the PFD crystal 3200 from the beginning of the first high frequency photon and exit the edge of the frequency conversion region. In some embodiments, phase matching between two wavelengths can be achieved in a particular crystal by controlling the polarization direction of the beam with respect to the crystal axis. The high frequency beam is automatically polarized along its preferential phase matching axis.

In some embodiments, phase matching is a function of refractive index, which is a function of propagation relative to crystal axes, polarization, and crystal temperature. In some embodiments, a particular crystal maintained at a particular temperature for a particular input wavelength is particularly insensitive to propagation angle and/or bandwidth. Frequency conversion in such cases is called non-critical phase matching (NCPM). Thus, for example, frequency doubling a 1064 nm beam with LBO maintained at 149.1° C. allows the beam to be focused into a relatively long crystal. In some embodiments, the focal length and interaction length are then optimized. However, NCPM is sensitive to temperature and possibly also to absorption of light. The absorption rate of green light is approximately four times that of infrared light.

In some embodiments of the present invention, a novel apparatus 3000 configured for frequency doubling of optical radiation is provided, as shown in Figures 17A-17C.
This device 3000
at least two consecutive nonlinear crystals (NLCs) 3100, 3200, 330 comprising a first NLC 100, at least one second NLC 3200 and an optional subsequent NLC 3300;
The first NLC 100 receives a fundamental beam 3101 at fundamental frequency (FF) and emits a weak second harmonic beam 3102 at second harmonic frequency (FH) along with a strong residual beam 3103 at fundamental frequency (FF). wherein the power ratio between the weak second harmonic beam 3102 and the fundamental beam 3101 is less than 5×10 ⁻³ :1;
At least one second NLC 3200 and optional subsequent NLC 3300 combine the residual beams 3103, 3203 at the fundamental frequency (FF) and the second harmonic frequency (FH) from the previous NLC 3100, 3200. After receiving the wave beams 3102, 3202 and optionally adjusting their phase difference for optimum frequency doubling, the strong frequency-doubled beams 3202, 3302 at the second harmonic frequency (FH) are applied to the fundamental frequency ( FF) remnant beams 3203, 3303, the power ratio between the strong frequency doubled beams 3202, 3302 and the fundamental beam 3101 is greater than 0.3:1.

In some embodiments, the apparatus 3000 pre-receives residual beams 3103, 3203 at the fundamental frequency (FF) and the second harmonic frequency (FH ) with the second harmonic beams 3102, 3202. In some embodiments, the PMC includes a chromatic dispersive element whose integral value can be controlled by tilt or applied voltage.

Figures 17A and 17B show a device 3000 with only one NLC multiplier 3200 and Figure 17C shows two NLC multipliers 3200, 3300 (a first NLC multiplier 3200 and a second NLC multiplier 3300). shows an apparatus with 17A and 17B show the device 3000 with a PMC 3502 placed in front of the first NLC multiplier 3200. FIG. FIG. 17C shows a device comprising two PMCs 3502 , 3503 , one PMC 3502 placed before a first NLC multiplier 3200 and the other PMC 3502 placed before a second NLC multiplier 3300 .

In some embodiments, the apparatus 3000 samples the intense frequency doubled beams 3202, 3302 and adjusts the PMCs 3502, 3503 accordingly to maximize the output of the intense frequency doubled beams 3202, 3302 over a wide range of operating conditions. further comprising at least one feedback and control system 3602, 3603 configured to enable

FIG. 17B samples the strong frequency-doubled beam 3202 emitted from the second NLC 3200 (which is the first NLC multiplier) and correspondingly placed before the first NLC multiplier 3200. A feedback and control system 3602 configured to regulate PMC 3502 is shown. FIG. 17C samples a strong frequency-doubled beam 3302 emitted from a third NLC 3300 (which is the second NLC multiplier) and correspondingly placed before the second NLC multiplier 3300. A feedback and control system 3603 configured to regulate PMC 3503 is shown. Both feedback and control system 3602 and system 3603 can be arranged in series.

In some embodiments, the feedback control system 3602, 3603 includes:
at least one measuring element (not shown) (e.g. a photodetector);
at least one processing element (not shown) configured to analyze data received from the at least one measurement element and, in response, provide control instructions for PMC adjustment;
at least one adjustment element (not shown) configured to adjust the PMCs 3502, 3503 (e.g., tilt the PMCs by a motorized rotating device and/or by voltages applied to the PMCs) in accordance with control instructions. .

In some embodiments, apparatus 3000 includes at least one oven 3701, 3702 (shown in FIG. 17B) each configured to regulate the temperature of NLCs 3100, 3200 (seeder NLC 3100 and/or NLC multiplier 3200). Prepare more.

In some embodiments, the length (LS) of the first NLC 3100 (seeder NLC) is significantly less than the length (LD) of the second NLC 3100 (NLC multiplier). In some embodiments, LS is 10% or less of LD (LS≦0.1 LD).

In some embodiments, the second NLC 3200 and any subsequent NLC 3300 comprise LBO material (for converting continuous wave lasers) and have a length (LD) greater than 40 mm.

In some embodiments, the fundamental frequency (FF) has the properties of infrared (IR) light (λF=1064 nm), so the second harmonic frequency (FH) is that of visible light (λH=532 nm) has the characteristics of

In some embodiments, each of the NLCs has a fundamental beam polarization along its crystal axis (Type 1) or at a 45 degree angle to its crystal axis. (Type 2).

In some embodiments, each of the NLCs includes at least one material selected from the group consisting of BBBO, KTP, LBO, CLBO, DKDP, ADP, KDP, LiIO3, KNbO3, LiNbO3, AgGaS2, and AgGaSe2.

In some embodiments, the dimensions of each lateral area 3210 of the NLC are larger than the dimensions of the input beam it receives.

In some embodiments, apparatus 300 further comprises at least one collimating lens 3401 configured to precisely collimate the input light beam. In some embodiments, apparatus 300 is configured to focus both the frequency-doubled beam and the residual beam onto a subsequent element, such as an NLC or PMC, optionally at its center (3215 in FIG. 17A). and at least one focusing element 3402,3403.

Some embodiments of the present invention provide novel methods for frequency doubling optical radiation.
This method
providing a fundamental beam at fundamental frequency (FF) and a nonlinear crystal (NLC) having a weak second harmonic beam at second harmonic frequency (FH);
launching by the NLC an intense frequency-doubled beam at the second harmonic frequency (FH) together with a residual beam at the fundamental frequency (FF);
the power ratio of the weak second harmonic beam to the fundamental beam is less than 5×10 ⁻³ to 1;
The power ratio between the strong frequency doubled beam and the fundamental beam is greater than 0.3:1.

In some embodiments, the providing step further comprises compensating for a phase mismatch between the fundamental beam and the weak second harmonic beam with a phase mismatch compensator (PMC), the method comprising: , further comprising controlling the PMC to enable maximizing the output of the intense frequency doubled beam.

Next, FIG. 18(A) and FIG. 18(B) are referred to. FIG. 18(A) schematically shows the temperature variation along the optical axis of a single crystal that is temperature regulated for low power conversion but undergoes heating when operated at high power. FIG. 18B shows the accumulated phase up to an arbitrary position Z within the crystal. The given temperature is (T0=149.1° C.) and T0(Z) is the on-axis temperature. As shown, the crystal is hottest in the focal region. This is because the area around the exothermic zone (beam) through which the heat passes is lowest at the focal position and the distance required for the heat to travel before exiting the heat transport zone (non-irradiated crystal) is the longest at the focal position. It is from. The temperature distribution is asymmetric with respect to the focal region. This is because more green light is produced as the beam propagates and more light is absorbed in the second half of the crystal. In this case MP increases monotonically because all points in the crystal become very hot.

As mentioned above, FIG. 18(A) schematically shows the temperature variation along the optical axis in a single LBO crystal placed in an oven set for low power frequency doubling of a 1064 nm beam. . In some embodiments, optimal multiplication occurs at 149.1°C. T0 is higher than the optimum temperature due to heating by the laser beam. The temperature profile is non-uniform because the beam is focused in the center of the crystal and because the green absorption is about four times the infrared absorption. Because of this heating, optimal multiplication does not occur.

FIG. 18B schematically shows the total phase difference between the fundamental beam and the multiplied beam. Note that the phase mismatch starts at the front surface of the crystal and builds up, even though most of the multiplication occurs in the focal region. Such MP accumulation has a large impact on frequency conversion in the focal region.

Next, FIGS. 19A to 19C will be referred to. FIGS. 19(A)-(C) show the conjugate seed position after readjusting the temperature of the PFD crystal with the aim of minimizing MP and achieving optimum temperature in the focal region where most of the frequency conversion takes place. Indicates to add a difference. In some embodiments, the conditions shown in FIGS. 18(A) and 18(B) are considered starting conditions.

FIG. 19(A) illustrates a solution based on temperature readjustment and phase offset provided by a seeder crystal, according to some embodiments. The first step is to readjust the temperature of the PFD, as in the conventional approach, as shown in FIG. 19(B). The feedback parameter is the maximum harmonic output after the first PFD. In some embodiments, the phase of the second harmonic seed beam produced by the seeder crystal is not optimal. In order to obtain the optimum phase difference with the seeder crystal, the PMC is changed as shown in FIG. 19(C). This two-step process is repeated until no further improvement is achieved. Simulation results show that the optimum phase difference is almost always obtained regardless of the initial phase difference, and that this optimum phase difference is very close to the conversion efficiency obtained with perfect PM.

In some embodiments, the device 3000 as described above can be incorporated into various systems.
Non-limiting examples include:
Systems for industrial applications such as irradiation of workpieces with low infrared absorption for the purpose of cutting, welding, surface treatment or further processing,
Aimed at generating femtosecond pulses with high repetition rate and high average power, or higher frequencies by further sum frequency mixing/additional frequency doubling, or second harmonic and below by adding optical parametric oscillators systems for scientific applications, such as pumping Ti:sapphire, for the production of tunable frequencies; and
Systems for medical applications where invasive procedures need to be performed quickly are included.

simulation test

20A, 20B and 20C, the results of a series of simulations performed with a 500 W input beam are shown. A 50 mm thick seeder crystal was used to generate a second harmonic seed beam with a phase difference significantly different from the conjugate phase difference required for MP correction of PFD-NLC. Note that much thinner crystals may be used in view of the required seeder beam power.

The models incorporated in the simulation are (a) to (g) below.
(a) Absorption per wavelength is axially dependent.
(b) the beam is focused in the center of the crystal;
(c) Lateral temperatures calculated in the beam (heating zone) and in the unirradiated zone (heat transport zone).
(d) Calculated phase based on thermo-optic coefficients and segment propagation lengths.
(e) Multiply segment by segment using SNLO.
(f) The crystal is divided into 7 segments. Each beam diameter is constant.
(g) Use the output for qualitative analysis.

Figures 20A-20C show three cases of axial temperature offset from the optimum temperature (dashed blue line). The input laser power was 500 W and a 50 mm seeder crystal was used.
The test results are as follows.
• The black line and bullets show the temperature change without reconditioning the oven from low power.
• The orange line and squares show the temperature offset after temperature adjustment for maximum multiplied output.
• The green line and triangles show the PMC reconditioning temperature and the temperature after the final (small) reconditioning.
The optimization goal was set at T0(Z)=149.1° C. in the center of the focal region. The heat transport along the input surface was assumed to be equal to the internal heat transport. We assumed zero heat transport across the input surface. Other boundary conditions were tested.

FIG. 20B is a diagram showing the phase difference between the fundamental wave (input) and the multiplied beam when the seeder NLC is used. The phase of the PMC was adjusted to obtain optimum multiplication in the middle of the PFD-NLC. This strategy always resulted in optimal multiplication.

FIG. 20C shows the green beam output as the beam propagates through the PFD. Note that the poor conversion prior to temperature and PMC reconditioning is significant. Also note that adding a PMC after temperature adjustment increases the output by a factor of 1.3, reaching the calculated output without phase mismatch.

Table 1 summarizes simulation results for a doubled 500 W input beam with and without a 50 mm seeder crystal.

Table 2 summarizes test results for a doubled 500 W input beam with and without a 10 mm seeder crystal.

The key takeaways from the above simulation tests are:
• Two independent parameters are required to correct for temperature and PMC phase mismatch. Although the temperature-induced phase mismatch was analyzed, the temperature plus PMC correction technique is applicable to other sources of MP.
• Acceptable phase matching was achieved over the long cross section of the PFD in the focused geometry analyzed and the use of a uniform temperature oven.
• Compensation can significantly improve performance. It can be improved to the performance level of PFD without generating MP.

The use of (seeder crystal + PMC) is perfectly compatible with multiple PFDs. In this case, each additional PFD is preceded by its corresponding PMC. Continuing simulations with a second PFD crystal suggests that about 350 W (70% conversion efficiency) is achieved.

One experimental test objective was to demonstrate that the incidence of a weak seed beam with a controlled fundamental harmonic phase difference, as in some of the embodiments above, was more effective from the "power multiplier" than the configuration without the seeder crystal. It was to demonstrate that better frequency multiplication could be generated.
This test is characterized by the following (a) to (c).
(a) lowering the first oven temperature for generating a weak seed beam; Seed beam profiles for different off-resonant temperatures are shown in FIG. The best profile is obtained when the temperature corresponds to the second peak that provides the desired output. In this case 190 mW was chosen.
(b) Determine the optimal second oven temperature of Pw≈220W+P2w≈30W.
(c) increase the second oven temperature to simulate additional heating; Do this twice. The first is done with the PMC held at a constant angle, and the second is done with the PMC rotated to obtain the maximum multiplication. Two seeder outputs were tested to distinguish between input-output amplification and phase effects.

Figures 22A and 22B show experimental results with and without a seeder beam and a comparison thereof. Fig. 22A is a seeder of 0.643W, Fig. 22B is a seeder of 0.188W, orange (upper) is "when the seeder beam is used", blue (lower) is "when the seeder beam is not used". be.
Figures 22A and 22B show
(1) At the optimum temperature of the 0.643 W seeder, there is a difference between the results of "using the seeder beam" and "using the seeder beam". This shows output amplification and phase effects.
(2) At the optimum temperature of 0.188 W seeder, there is no difference between the results of "using seeder beam" and "using seeder beam". At higher temperatures, it exhibits only phase mismatch effects. The difference (horizontal and/or vertical) indicates the improvement.

Figure 23 shows the added value when using the Cedar beam, calculated as follows.
(P _{2W-with seeder} -P _{2W-without seeder} )/(P _{2W-with seeder} ) vs 2nd oven temperature The maximum appears in the wings and does not return to double the peak, so it looks conservative.

In some embodiments, a constant power beam is produced with variations on the order of SD=±1.5% for commercial products. The wider the temperature bandwidth of the multiplier, the easier it is to maintain this stability.

Table 3 shows the width of the temperature regulation curve at the 98.5% level. Therefore, the "without seeder beam (no seeder)" bandwidth is less than the oven control circuit's capability. The "with seeder beam (with seeder)" bandwidth is feasible.

FIG. 24 shows that the seeder beam provides a phase effect by presenting the green output beam versus PMC rotation.
(1) Inverse conversion (output reduction) can be caused only by phase control.
(2) Output can be adjusted by rotating the PMC to fix the oven temperature constant.
(3) Only the 0.19W seeder caused a 7W power drop. Therefore, phase control was confirmed.

Thus, according to some of the embodiments described above, the seeder simulation tests described above lead to the conclusion that green light output >200 W from a single beam can be provided using a seed beam. be killed.

Performance Enhancement of Harmonic Conversion Systems Using Actively Controlled Phase Mismatch Compensators Between Two Crystals

In some embodiments, the present invention provides the addition of dynamic control over the PMC using feedback or lookup tables to enhance the performance of frequency conversion systems. In some embodiments, this provides at least one of improved stability in the presence of temperature fluctuations in the oven containing the crystal, changes in the average power of the laser, and the ability to tune the harmonic beam. It is possible to realize one.

In some embodiments, the PMCs described herein consist of glass windows. In some embodiments, PMC is generally applicable to any optical element that exhibits chromatic dispersion that is a function of externally controllable parameters.

25A, 25B, and 25C show apparatus 4000 configured to frequency-multiply an input optical radiation 4101 to provide an output beam 4400 having a second harmonic frequency 4302. FIG.
This device 400
At least two consecutive nonlinear crystals (NLCs) 4200, 4300, each NLC having a first beam 4201, 4203 at the fundamental frequency (FF) and optionally a second beam from the previous NLC. To receive a second beam 4202 at harmonic frequency (FH) and to emit strong frequency double multiple beams 4202, 4302 at second harmonic frequency (FH) along with remnant beams 4203, 4303 at fundamental frequency (FF). said at least two consecutive nonlinear crystals (NLC) 4200, 4300 configured;
at least one phase mismatch compensator (PMC) 4503 disposed between two NLCs, a residual beam 4203 at the fundamental frequency (FF) and a second harmonic beam at the second harmonic frequency (FH); 4202 before being received by a subsequent NLC;
A motorized rotator 4650 for each PMC configured to actively rotate the PMC, thereby actively correcting the phase relationship between the residual beam and the second harmonic beam. and the motorized rotating device 4650 for adjusting.

In some embodiments,
This device 4000
The PMC is tilted in a continuous or step-wise manner by a motorized rotating device to sample the intense frequency doubled beam in real time and correspondingly to continuously allow maximum output of the intense frequency doubled beam. Further comprising at least one configured feedback and control system.

In some embodiments, the feedback and control system controls at least one beamsplitter 4610, at least one measurement element (eg, photodiode 4620), at least one processing element 4630, and a motorized rotating device 4650. and at least one control element 4640 configured to.

In some embodiments, the PMC includes an optically transparent window that exhibits chromatic dispersion and is configured such that the distance required for the beam to pass through the window varies with the rotation angle of the window. In some embodiments, the PMC includes a plate that exhibits chromatic dispersion (e.g., a transparent plate that is polished on both sides), and the distance it takes for the beam to pass through the plate is relative to the rotation angle of the plate. is configured to change to

In some embodiments, the motorized rotating device 4650 is configured to rotate the PMC in stepped and/or continuous motion in a continuous real-time manner.

In some embodiments, the motorized rotating device is further configured to rotate the PMC in a dithered fashion bounded by upper and lower limits.

In some embodiments, the feedback and control system is configured to use a dither form to provide at least one of the following.
minimizing the inverse transform in the subsequent NLC, thereby maximizing the power of the output beam;
maximizing the inverse transform in the subsequent NLC, thereby minimizing the power of the output beam;
regulating the power of the output beam to a predetermined value between maximum and minimum values (static or dynamic operating conditions, optionally selected from changing input laser power and changing oven temperature) inside).

In some embodiments, the motorized rotator is configured to rotate the PMC in toggle mode between a maximum harmonic conversion state and a minimum harmonic conversion state to turn the output beam on and off. ing.

In some embodiments, the motorized rotating device is configured to rotate the PMC to provide flat top pulses with controlled rise and fall times and controllable durations.

In some embodiments, the motorized rotating device is configured to provide shaped harmonic pulses by rotating the PMC according to a lookup table.

In some embodiments, apparatus 4000 further comprises at least one dichroic beam splitter 4801 configured to separate at least a portion of residual beam 4303 from output beam 4400 .

In some embodiments, the power ratio between the emitted strong frequency doubled beam and the emitted fundamental beam is greater than 0.3:1.

In some embodiments, apparatus 4000 further comprises at least one oven each configured to regulate the temperature of the NLC.

Some embodiments are configured to actively control the PMC to minimize output fluctuations due to temperature fluctuations in the oven housing the NLC.

In some embodiments, at least one of the NLCs comprises an LBO and its length (LD) is sufficient to achieve significant harmonic light. In some embodiments, at least one of the NLCs comprises an LBO and has a length (LD) greater than 40 mm.

In some embodiments, the fundamental frequency (FF) has the properties of infrared (IR) light (λF = 1064 nanometers nm), so the second harmonic frequency (FH) is characteristic of visible light (λH = 532 nm).

In some embodiments, each of the NLCs is configured to have a fundamental beam polarization along its crystal axis or at a 45 degree angle to its crystal axis. ing.

In some embodiments, each of the NLCs comprises at least one material selected from the group consisting of BBBO, KTP, LBO, CLBO, DKDP, ADP, KDP, LiIO3, KNbO3, LiNbO3, AgGaS2, AgGaSe2.

In some embodiments, the size of each lateral area of the NLC is larger than the size of the input beam it receives.

In some embodiments, the apparatus 4000 further comprises at least one achromatic focusing element 4231, 4232, 4232 configured to focus the fundamental and harmonic beams to the NLC.

In some embodiments of the present invention, apparatus 4000 further comprises at least one collimating lens 4406 configured to make its passing beam rays substantially collimated. In some embodiments, apparatus 4000 includes at least one focusing element, such as an achromatic lens or mirror, configured to focus both the frequency-doubled beam and the residual beam onto a subsequent element, such as an additional NLC. 4404, 4405 are further provided.

In some embodiments, the PMC consists of a thin (approximately 1 mm) antireflective coated fused silica window. In some embodiments, the inherent chromatic dispersion of the material is used to add a controllable amount of phase difference between the fundamental and harmonic beams passing through the material.

The following examples demonstrate that enhanced performance is achieved through active control of the PMC, according to some embodiments. In some embodiments, the PMC is attached to a motorized rotating (or tilting) base 4650 . In some embodiments, as shown in FIGS. 26A and 26B, the fundamental harmonic phase difference increases with the rotation angle α of the PMC. As the rotation (or tilt) angle α (angle from the PMC oriented perpendicular to the beam, α=0) increases, the optical path through the PMC increases. FIG. 26B: P1>P0, P0 is the optical path when α=0, and P1 is the optical path when α>0.

In some embodiments, the optimal rotation angle that provides the optimal output beam (e.g., user-specified output beam) 4400 is based on a lookup table (predetermined table based on previous databases). or as a result of rotating to a predetermined position using the feedback system 4603 shown in FIGS. 25A and 25B. FIG. 25C shows the device without the feedback system. In some embodiments, as shown in FIGS. 25A and 25B, feedback is achieved by sampling the output beam 4400 using a power measurement detector (eg, photodiode, 4620 in FIG. 25B). . In some embodiments, in both embodiments (lookup table and feedback system), a computer (or microprocessor) 4630 is used to transmit control signals to motorized rotating device 4650 using driver electronics 4640 .

In some embodiments, a feedback algorithm is used to continuously adjust the rotation angle of the PMC to find and maintain the maximum multiplication efficiency, thereby achieving a constant crystal Reduce green light output fluctuations (eg, by a factor of 2) caused by temperature stability limitations of the oven used to maintain the temperature. In some embodiments, feedback control can be used to correct the angle of the PMC to overcome changes in laser input power that cause changes in crystal temperature due to differences in light absorption.

In some embodiments, the opposite of frequency multiplication is an inverse transform. Frequency-doubled light generated in the first crystal can be converted back to the fundamental frequency in the second crystal by adjusting the phase difference. PMC is effective for introducing such an inverse transform phase difference. Therefore, by rotating the PMC, the frequency multiplication can be maximized or minimized. As a result, by switching the angle of the PMC between low green light output (LG) and high green light output (HG) to toggle the beam output between "off" or "on", Harmonic pulses can be generated.

In some embodiments, as shown in FIG. 27, a method 5000 is provided for activating (“on”) and/or deactivating (“off”) the frequency doubled output beam from the apparatus 4000 described above. be done.
The method 5000 includes:
a sampling step 4710 that samples in real time and measures the output beam;
a decision step 4720 continuously or frequently determining whether the output beam has reached a maximum value (for "on" output) or a minimum value (for "off"output);
a step 4740 of rotating the PMC if the determination at decision step 4720 is "NO" and then returning to sampling step 4710 to repeat the method;
If the determination at decision step 4720 is "YES," then maintain the current PMC rotation angle αMAX (or αMIN) and then return to sampling step 4710 to determine the dynamic input beam and/or dynamic oven temperature. and repeating the method.

In some embodiments, the "on"/"off" states are long enough so that optimal maximum/minimum values can be achieved. In some embodiments, rotating the PMC toggles the PMC between two predetermined states for faster "rise" or "fall" times ("on"/"off"). to rapidly adjust the harmonic output beam.

Apparatus 4000 and method 5000 have been tested and demonstrated that the rise time (30 milliseconds) of output beam 4400 activation ("on") is limited only by the particular data communication hardware used. In some embodiments, the rise time is limited only by the inertia of the rotating system, the torque, and the accuracy of the motorized rotating device toggling between two positions (“on”/“off”). In this way, the rise time in phase toggle mode can be less than 1 ms.

In some embodiments, FIG. 25B schematically illustrates the device 4000 described above including two nonlinear crystals (NLCs) 4200, 4300 in the configuration used for the following demonstration tests. The demonstrated harmonic conversion setup uses two nonlinear crystals placed in an oven and separated from each other by an actively controlled phase mismatch compensator (PMC) plate. The PMC4503 is mounted on a motorized rotator whose position is computer controlled using feedback provided by a lookup table or photodiode that samples the harmonic output beam. In this setup the beam is focused on each crystal to maximize the conversion efficiency per crystal. In some embodiments, as used in this test setup, the NLC comprises lithium triborate (LBO) oriented for Type 1 non-critical phase matching. As shown, the NLC is housed in a resistive oven that maintains a temperature of approximately 149.1±0.15°C. The optimum temperature varies as a function of input power due to optical absorption at the fundamental and harmonic wavelengths. The degree of crystal absorption is an important factor. A typical variation in optimum temperature is several degrees of fundamental beam power between 10W and 250W.

In some embodiments, sensitivity to temperature scale changes is inversely proportional to crystal length. In the devices tested, the individual crystals were at least 40 millimeters (mm) long, and two output crystal multipliers were provided per device. The requirement is typically ±1% harmonic output stability. This translates into an oven temperature stability requirement of about ±0.04° C. with two crystal passes (tested by passing one crystal twice) undergoing identical temperature changes in this example. be done. Such temperature stability exceeds the capabilities of most ovens and control circuits. The oven's control circuit operates by applying an electrical pulse to the heating resistor when the temperature drops below a predetermined level. This raises the crystal temperature, but always causes an overshoot.

Figures 28A and 28B schematically illustrate variations in crystal temperature and multiplied output over time due to undershoot/overshoot in the oven's control circuitry, according to some embodiments of the present invention. FIG. 28A shows the change in oven temperature below the optimum temperature for frequency doubling, and FIG. 28B shows the oven temperature above the optimum temperature for frequency doubling. In a typical system, the characteristic time for heating and cooling is about 1 minute. As shown in FIG. 28A, the harmonic light output variation mimics the frequency of oven temperature variation when the temperature does not exceed the optimum temperature point. As shown in FIG. 28B, when the oven temperature exceeds the optimum temperature point, the frequency of the harmonic output fluctuations increases to twice the frequency of the temperature fluctuations (if the temperature fluctuations are symmetrical around the optimum temperature point). . This result is caused by the fact that the harmonic power peaks (on the way up or down) every time the optimum temperature point is exceeded, but the power falls off for both positive and negative ΔT.

In some embodiments, temperature changes introduce a phase mismatch between the fundamental light and the harmonic light, so by adding a conjugate phase using a phase mismatch compensator (PMC) plate, the oven The resulting phase mismatch can be nullified. In some embodiments, the temperature of the oven is changed continuously, so the rotation of the PMC is also changed continuously. For this reason, the PMC is placed on a motorized rotary stage. In some embodiments, the rotation angle of the PMC is varied by dither control. In some embodiments, dither control is an intentionally applied form of noise that is used to randomize the quantization error and prevent large scale patterns.

FIG. 29 illustrates output stabilization with dither control for rotating PMCs configured to overcome oven undershoot/overshoot, according to some embodiments of the present invention. As shown, active PMC responses are indicated by vertical lines in time. At the end of each response period, the direction of rotation and speed are evaluated. Due to the time delay until the crystal begins to heat or cool and the PMC re-turns, an error occurs and the output drops. As shown, a high frequency, small amplitude, rotational dither control is applied to the PMC. In some embodiments, the upper dither frequency limit is determined by the physical inertia plus the integral of the feedback signal and the response time of the system. In some embodiments, the lower dither frequency limit is determined by application requirements or by the height/depth of output fluctuations caused by dither. In some embodiments, the optimum PMC induction phase is not constant but serrated with a period equal to the period of the oven temperature fluctuations. In addition to this slow change, there is a dither phase change. If the dither control properly tracks oven variations, the harmonic output will vary at twice the dither frequency. If there is an error in the PMC phase (e.g. immediately after the crystal starts to heat up after powering on the oven, or if there is a lag between processing the feedback signal and transmitting the control signal to the PMC), The output drops and high frequency fluctuations drop to the dither frequency.

In some embodiments, dither control with feedback is used to optimize the angle of the PMC after changing operating conditions, as shown in FIG. Also, according to some embodiments, dither control with feedback reduces variation from a typical value of about ±3.7% with static PMC, as shown in FIG. is used to keep the harmonic output at a maximum value. Also, according to some embodiments, continuous dither control is used to adjust the PMC to about ±1.5 when operating the PMC with active feedback control, as shown in FIG. 31(B). 6% (upper right part shows a magnified view of the time period from 1440.5 to 1442.7 seconds). A feedback photodiode was monitored for these measurements. Note: Figure 30 shows the output green light output when the feedback controlled PMC is rotated to the maximum level of output (P2ω = 80W). The serrations on power ramp-up are the result of the dither control of the PMC. Data were acquired using a feedback photodiode. 31(A) and 31(B) show a case where PMC stabilization is not performed by continuous feedback control (FIG. 31(A)) and a case where PMC stabilization is performed by continuous feedback control ( Fig. 31(B) shows a comparison of output fluctuations. Figures 31(A) and 31(B) show a 10 minute window out of a 60 minute run time. A feedback photodiode was monitored for these measurements.

In some embodiments, additional insight can be gained by looking at power meter data in the frequency domain. This is illustrated in FIG. 32, analyzing a one hour run using the Fast Fourier Transform (FFT). The lower graph shows the case with the stabilization algorithm and the upper graph shows the case without the stabilization algorithm. When run without the stabilization algorithm, the harmonic conversion started with optimal phase matching but drifted over time. Thus, two offset peaks were observed at the characteristic temperature response frequency of the oven and its double frequency. Also note that just past the constant power spike at 0 Hz there is a raised low frequency output. Note: At 0 Hz there is a point with a value equal to 1. This is the constant power component of the signal. In some embodiments, a perfectly stable beam includes only this one point. This is another indicator of output drift. With continuous dither stabilization, the results are very different. The output fluctuations caused by the oven were reduced by a factor of about 5, and the low frequency drift was also greatly reduced. The dither stabilization algorithm produced high frequency content beyond the range of the plot. These frequencies exceeded the frequency response of the Ophir 50 (150) output meter I was using.

In some embodiments, high-level inversion is achieved and maintained using the same techniques used to maximize harmonic conversion in two NLC devices 4000 . In some embodiments, the only parameter that is changed is the infrared (IR)-green retardation. A simulation of this effect is shown in FIG. FIG. 33 shows Smith nonlinear optics (SNLO) simulations of the effect on harmonic output of rotating the PMC plate for various input outputs. A typical low green light output to high green light output ratio of 10-fold or more was experimentally achieved at high power (LG/HG<0.10). In some embodiments, this result can be used to modulate (“on”/“off”) a high power continuous wave (CW) green beam. This is important because just turning the fundamental beam on and off only slightly increases the rise time. Note: The reason is that due to the high power multiplication the oven temperature is reduced to allow for IR+green absorption. When the laser is first turned on, the temperature is too low and the multiplication efficiency is low. As infrared light is absorbed, the temperature of the crystal increases and more green color is produced. Absorption of green light causes the temperature of the crystal to rise further, approaching the optimal high power value. In some embodiments, full multiplication efficiency cannot be achieved until the absorption of the fundamental light followed by the green light brings the crystal into thermal equilibrium.

Figures 34A and 34B are achieved according to some embodiments by quickly turning "on" the input laser beam shown in Figure 34A or by toggling the position of the PMC as shown in Figure 34B. shows a comparison of rise time (minimum output to maximum output). The IR input power was 246W and the maximum green power was 75W. A thermopile power meter (τ _rise =2 sec) was used to make the measurements shown in FIG. 34A and a feedback photodiode was used to obtain the trace shown in FIG. 34B (τ _rise =30 ms). In this test setup, the rise time of the PMC activation system is limited by the communication time between the photodiode and the computer and the communication time between the computer and the PMC rotation stage. The dashed line indicates the rise time of the fiber laser during fast turn-on. The dashed line indicates a much slower rise of the green output. This slow response is due to the time required to reach thermal equilibrium, first due to IR absorption and then due to green absorption as more green output is produced. The very fast response when using the PMC toggle is a result of the fact that the first crystal is in thermal equilibrium while the second crystal is partially heated by infrared absorption. . Sub-millisecond rise times can be achieved by minimizing inertia and proper selection of the motorized rotator and control circuitry.

Note that more complex pulse shaping is a simple extension of this technique. In some embodiments, arbitrarily shaped pulses can be generated as long as the time dependent PMC relative angle can be obtained, programmed and then executed.

In some embodiments, the device 4000 as described above can be incorporated into various systems.
Non-limiting examples include:
Systems for industrial applications such as irradiation of workpieces with low infrared absorption for the purpose of cutting, welding, surface treatment or further processing,
Aimed at generating femtosecond pulses with high repetition rate and high average power, or higher frequencies by further sum frequency mixing/additional frequency doubling, or second harmonic and below by adding optical parametric oscillators systems for scientific applications, such as pumping Ti:sapphire, for the production of tunable frequencies; and
Examples include systems for medical applications where invasive procedures need to be performed quickly.

While certain features of the invention have been illustrated and described herein, various alterations, substitutions, changes, and equivalents will occur to those skilled in the art. It is therefore to be understood that the appended claims are intended to cover all such modifications and variations that fall within the scope of this invention.

Claims (79)

by a laser system comprising at least one seed laser device and a coherent beam combining (CBC) system configured to receive a seed beam of said seed laser device and selectively provide an amplified laser beam; A method for conditioning a laser beam comprising:
The coherent beam combining (CBC) system comprises:
a plurality of phase adjusters, each arranged to enable constructive or destructive beam interference at the CBC point, a seed beam, a plurality of optical amplifiers, at least one beam splitter, and optionally the plurality of phase adjusters configured to be optically connected to at least one beam combiner;
at least one control circuit configured to monitor the beam interference at the CBC point and control at least one of the plurality of phase adjusters accordingly;
The method is
providing the laser beam by controlling the phase adjuster to activate the laser beam to provide constructive beam interference at the CBC point;
stopping providing the laser beam by controlling the phase adjuster to deactivate the laser beam to provide destructive beam interference at the CBC point;
A method characterized by: The method of claim 1, wherein
The step of activating the laser beam by controlling the phase adjuster to provide the constructive beam interference adjusts the phase adjuster to provide the constructive beam interference at a maximum intensity. A method, comprising: 3. The method of claim 2, wherein
The step of controlling the phase adjusters to provide the destructive interference and deactivating the laser beam includes controlling half of the adjusted phase adjusters to the laser beam. adding a half-phase (π) at . 3. The method of claim 2, wherein
said step of controlling said phase adjusters to provide said destructive interference to deactivate said laser beam comprises adjusting some of said adjusted phase adjusters; A method characterized by 5. The method of claim 4, wherein
A method, wherein each of said phase adjusters is adjusted individually. 3. The method of claim 2, wherein
further comprising adjusting the laser beam by adjusting some of the phase adjusters adjusted to provide the laser beam at maximum intensity;
A method, wherein adjusting the phase adjuster includes bringing the intensity of the laser beam to an intensity equal to a predetermined percentage of the maximum intensity. The method of claim 1, wherein
The step of controlling the phase adjuster to provide the destructive beam interference to deactivate the laser beam comprises controlling the phase adjuster to provide the destructive beam interference at a minimum intensity. A method, comprising the step of adjusting. A method for modulating a laser beam provided by a laser system comprising:
The laser system is
at least one seed laser device;
a fast optical modulator (FOM) configured to receive the seed beam of the seed laser device and adjust its bandwidth;
a coherent beam combining (CBC) system configured to receive the bandwidth-adjusted seed beam and provide an amplified laser beam;
The method is
said fast optical modulator ( activating said laser beam by controlling a FOM), thereby providing said laser beam;
controlling the fast optical modulator (FOM) to provide the seed beam with a second bandwidth (Δω2; Δω2>Δω1) set to disable constructive interference at the CBC point; and deactivating the laser beam, thereby stopping providing the laser beam by
A method characterized by: 9. The method of claim 8, wherein
The coherent beam combining (CBC) system comprises:
a plurality of phase adjusters, each arranged to enable constructive beam interference at a CBC point, said adjusted seed beam, a plurality of optical amplifiers, at least one beam splitter, and optionally the plurality of phase adjusters configured to be optically connected to at least one beam combiner of
at least one control circuit configured to monitor the beam interference at the CBC point and control at least one of the plurality of phase adjusters accordingly;
said step of activating said laser beam further comprising controlling said phase adjuster to provide said constructive beam interference;
A method characterized by: 10. The method of claim 9, wherein
wherein said step of controlling said phase adjuster to provide said constructive beam interference includes adjusting said phase adjuster to provide said constructive beam interference at a maximum intensity. and how to. A method for modulating a laser beam provided by a laser system comprising:
The laser system is
a coherent beam combining (CBC) system configured to receive a seed laser beam and provide an amplified laser beam;
a first seed laser device configured to provide a first seed beam having a first wavelength (λ1);
a second seed laser device configured to provide a second seed beam having a second wavelength (λ2; λ2≠λ1) different from the first wavelength;
an optical switch configured to link only one of the first seed beam and the second seed beam to the coherent beam combining (CBC) system;
The coherent beam combining (CBC) system comprises:
a linked seed beam, a plurality of optical amplifiers, at least one beam splitter, and a plurality of phase adjusters, each arranged to enable constructive or destructive beam interference at a CBC point; the plurality of phase adjusters configured to be optically connected to an optional at least one beam combiner;
at least one control circuit configured to monitor the beam interference at the CBC point and control at least one of the plurality of phase adjusters accordingly;
The method is
controlling the optical switch to link the first seed beam to the coherent beam combining (CBC) system to activate the laser beam and controlling the phase adjuster to enable constructive beam interference; and thereby providing said laser beam;
controlling the optical switch to link the second seed beam to the coherent beam combining (CBC) system to deactivate the laser beam to disable the constructive beam interference, thereby ceasing to provide the beam;
A method characterized by: 12. The method of claim 11, wherein
wherein said step of controlling said phase adjuster to provide said constructive beam interference includes adjusting said phase adjuster to provide said constructive beam interference at a maximum intensity. and how to. A method for modulating a laser beam provided by a laser system comprising:
The laser system is
a coherent beam combining (CBC) system configured to receive a seed laser beam and provide an amplified laser beam;
a first seed laser apparatus configured to provide a first seed beam having a first bandwidth (Δω1);
a second seed laser apparatus configured to provide a second seed beam having a second bandwidth (Δω2; Δω2>Δω1) wider than the first bandwidth;
an optical switch configured to link only one of the first seed beam and the second seed beam to the coherent beam combining (CBC) system;
the first bandwidth (Δω1) is set to enable the constructive beam interference at a CBC point of the coherent beam combining (CBC) system;
the second bandwidth (Δω2) is set to disable the constructive beam interference at the CBC point;
The method is
controlling the optical switch to link the first seed beam to the coherent beam combining (CBC) system to activate the laser beam to enable the constructive beam interference, thereby providing a step;
controlling the optical switch to link the second seed beam to the CBC system and deactivate the laser beam to disable the constructive beam interference, thereby stopping the provision of the laser beam; ,including,
A method characterized by: 14. The method of claim 13, wherein
The coherent beam combining (CBC) system comprises:
a plurality of phase adjusters, a linked seed beam, a plurality of optical amplifiers, at least one beam splitter, each arranged to enable constructive or destructive beam interference at said CBC point; and the plurality of phase adjusters configured to be optically connected to and optionally at least one beam combiner;
at least one control circuit configured to monitor the beam interference at the CBC point and control at least one of the plurality of phase adjusters accordingly;
said step of activating said laser beam further comprising controlling said phase adjuster to provide said constructive beam interference;
A method characterized by: 15. The method of claim 14, wherein
wherein said step of controlling said phase adjuster to provide said constructive beam interference includes adjusting said phase adjuster to provide said constructive beam interference at a maximum intensity. and how. A method for modulating a laser beam provided by a laser system comprising:
The laser system is
a coherent beam combining (CBC) system configured to receive a seed laser beam and provide an amplified laser beam;
a first seed laser device configured to provide a first seed beam having a first wavelength (λ1);
a second seed laser device configured to provide a second seed beam having a second wavelength (λ2; λ2≠λ1) different from the first wavelength;
an optical switch configured to link only one of the first seed beam and the second seed beam to the coherent beam combining (CBC) system;
receive the amplified laser beam, transmit the beam having the first wavelength (λ1) to the output of the laser system, and reflect the beam having the second wavelength (λ2), thereby providing an output laser beam a dichroic mirror configured to selectively provide the beam;
The method is
controlling the optical switch to link the first seed beam to the coherent beam combining (CBC) system to activate the laser beam, thereby transmitting the laser beam to provide the laser beam; a step;
controlling the optical switch to link the second seed beam to the coherent beam combining (CBC) system to deactivate the laser beam, thereby reflecting the laser beam to provide the laser beam; stopping the
A method characterized by: 17. The method of claim 16, wherein
The coherent beam combining (CBC) system comprises:
a linked seed beam, a plurality of optical amplifiers, at least one beam splitter, and a plurality of phase adjusters, each arranged to enable constructive or destructive beam interference at a CBC point; the plurality of phase adjusters configured to be optically connected to an optional at least one beam combiner;
at least one control circuit configured to monitor the beam interference at the CBC point and control at least one of the plurality of phase adjusters accordingly;
said step of activating said laser beam further comprising controlling said phase adjuster to provide said constructive beam interference;
A method characterized by: 18. The method of claim 17, wherein
wherein said step of controlling said phase adjuster to provide said constructive beam interference includes adjusting said phase adjuster to provide said constructive beam interference at a maximum intensity. and how to. A method for modulating a laser beam provided by a laser system comprising:
The laser system is
a master oscillator power amplifier (MOPA) configured to receive a seed laser beam and provide an amplified laser beam;
a first seed laser device configured to provide a first seed beam having a first wavelength (λ1);
a second seed laser device configured to provide a second seed beam having a second wavelength (λ2; λ2≠λ1) different from the first wavelength;
an optical switch configured to link only one of the first seed beam and the second seed beam to the master oscillator power amplifier (MOPA);
receive the amplified laser beam, transmit the beam having the first wavelength (λ1) to the output of the laser system, and reflect the beam having the second wavelength (λ2), thereby providing an output laser beam a dichroic mirror configured to selectively provide the beam;
The method is
controlling the optical switch to link the first seed beam to the master oscillator power amplifier (MOPA) to activate the laser beam, thereby transmitting the laser beam to provide the laser beam; a step;
controlling the optical switch to link the second seed beam to a coherent beam combining (CBC) system to deactivate the laser beam, thereby reflecting the laser beam and providing the laser beam; stopping; and
A method characterized by: A method for modulating a laser beam provided by a laser system comprising:
The laser system is
at least one seed laser device;
at least one optical polarization combiner (OPC) configured to receive a seed beam of said seed laser device and adjust its polarization direction, said polarization direction adjustment comprising at least two polarization components in said seed beam; the optical polarization combiner (OPC), wherein one of the polarization components has a predetermined polarization direction (P1), and
a coherent beam combining (CBC) system configured to receive the polarization adjusted seed beam and provide an amplified laser beam;
receiving the amplified laser beam, transmitting only the beam component having the predetermined polarization direction (P1) to the output of the laser system and reflecting the beam component having the other polarization direction, thereby causing the laser beam to a polarizing beam splitter (PBS) configured to selectively provide
The method is
activating said laser beam by controlling said optical polarization combiner (OPC) to provide a beam component having said predetermined polarization direction (P1) at an intensity (I1) greater than 50% of the total intensity of the beam; transforming, thereby providing said laser beam;
said laser beam by controlling said optical polarization combiner (OPC) to provide a beam component having said predetermined polarization direction (P1) at an intensity (I1) less than or equal to 50% of the total intensity of said laser beam; deactivating, thereby stopping providing said laser beam;
A method characterized by: 21. The method of claim 20, wherein
by controlling the optical polarization combiner (OPC) to provide a beam component with the predetermined polarization direction (P1) having an intensity (I1) equal to a predetermined fraction of the total intensity of the seed laser beam; A method, further comprising adjusting a laser beam. 21. The method of claim 20, wherein
The coherent beam combining (CBC) system comprises:
a plurality of phase adjusters, said polarization adjusted seed beam, a plurality of optical amplifiers, at least one beam splitter each arranged to enable constructive or destructive beam interference at a CBC point; , and optionally the plurality of phase adjusters configured to be optically connected to at least one beam combiner;
at least one control circuit configured to monitor the beam interference at the CBC point and control at least one of the plurality of phase adjusters accordingly;
The method is
further comprising controlling the phase adjuster to provide the constructive beam interference at the CBC point at least during the step of activating the laser beam;
A method characterized by: 21. The method of claim 20, wherein
The optical polarization combiner (OPC) is
A beam splitting assembly for receiving an input beam having a first polarization direction (P1) and a first output beam (B1(I1 , P1)) and a second output beam (B2(I2, P1)) having said first polarization direction (P1) and a second intensity (I2), said first the beam splitting assembly, wherein the sum of the intensity of and the second intensity (I1+I2) is equal to the intensity of the input beam;
a polarization converter configured to receive one of the first output beam and the second output beam (B1 or B2) output from the beam splitting assembly and convert the polarization thereof;
a polarizing beam splitter (PBS) for receiving the first output beam (B1(I1,P1)) and the polarization converted second output beam (B2(I2,P2)) and dividing them into the polarizing beam splitter (PBS) or coupler configured to combine to produce a third beam, polarization converted with the first output beam (B1(I1,P1)); receiving the second output beam (B2(I2, P2)) and combining them and then splitting them into two output beams, only one of the two split output beams being subjected to the coherent beam combining (CBC) ) the coupler configured to provide as an input to the system;
A method characterized by: 24. The method of claim 23, wherein
The beam splitting assembly comprises:
a beam splitter configured to receive an input beam and split the input beam into two beams;
a phase adjuster configured to adjust the phase of one of the two beams;
By receiving the two beams and providing their interference at two interference locations, the first output beam (B1(I1,P1)) and the second output beam (B2(I2,P1) ) and a coupler configured to provide
An electronic controller for monitoring one of said two interference locations and controlling said phase adjuster accordingly to enable constructive or destructive beam interference at the monitored interference location. and the electronic controller configured to provide destructive or constructive beam interference at unmonitored interference locations;
the step of controlling the optical polarization combiner (OPC) includes controlling the phase adjuster;
A method characterized by: A method for modulating a laser beam provided by a laser system comprising:
The laser system is
at least one seed laser device;
at least one optical polarization combiner (OPC) configured to receive a seed beam of said seed laser device and adjust its polarization direction, said polarization direction adjustment comprising at least two polarization components in said seed beam; the optical polarization combiner (OPC), wherein one of the polarization components has a predetermined polarization direction (P1), and
a master oscillator power amplifier (MOPA) configured to receive the polarization adjusted seed beam and provide an amplified laser beam;
receiving the amplified laser beam, transmitting only the beam component having the predetermined polarization direction (P1) to the output of the laser system and reflecting the beam component having the other polarization direction, thereby causing the laser beam to a polarizing beam splitter (PBS) configured to selectively provide
The method is
activating said laser beam by controlling said optical polarization combiner (OPC) to provide a beam component having said predetermined polarization direction (P1) at an intensity (I1) greater than 50% of the total intensity of the beam; transforming, thereby providing said laser beam;
said laser beam by controlling said optical polarization combiner (OPC) to provide a beam component having said predetermined polarization direction (P1) at an intensity (I1) less than or equal to 50% of the total intensity of said laser beam; deactivating, thereby stopping providing said laser beam;
A method characterized by: A laser system configured to modulate a laser beam, comprising:
at least one seed laser device;
at least one optical polarization combiner (OPC) configured to receive a seed beam of said seed laser device and adjust its polarization direction, said polarization direction adjustment comprising at least two polarization components in said seed beam; the optical polarization combiner (OPC), wherein one of the polarization components has a predetermined polarization direction (P1), and
a coherent beam combining (CBC) system configured to receive the polarization adjusted seed beam and provide an amplified laser beam;
receiving the amplified laser beam, transmitting only the beam component having the predetermined polarization direction (P1) to the output of the laser system and reflecting the beam component having the other polarization direction, thereby causing the laser beam to a polarizing beam splitter (PBS) configured to selectively provide a
An electronic control device,
activating said laser beam by controlling said optical polarization combiner (OPC) to provide a beam component having said predetermined polarization direction (P1) at an intensity (I1) greater than 50% of the total intensity of the beam; transforming, thereby providing said laser beam;
said laser beam by controlling said optical polarization combiner (OPC) to provide a beam component having said predetermined polarization direction (P1) at an intensity (I1) less than or equal to 50% of the total intensity of said laser beam; the electronic controller configured to deactivate, thereby stopping providing the laser beam;
A system characterized by comprising: 27. The system of claim 26, comprising:
The coherent beam combining (CBC) system comprises:
a plurality of phase adjusters, said polarization adjusted seed beam, a plurality of optical amplifiers, at least one beam splitter each arranged to enable constructive or destructive beam interference at a CBC point; , and optionally the plurality of phase adjusters configured to be optically connected to at least one beam combiner;
at least one control circuit configured to monitor the beam interference at the CBC point and control at least one of the plurality of phase adjusters accordingly;
A system characterized by: 27. The system of claim 26, comprising:
The optical polarization combiner (OPC) is
A beam splitting assembly for receiving an input beam having a first polarization direction (P1) and a first output beam (B1(I1 , P1)) and a second output beam (B2(I2, P1)) having said first polarization direction (P1) and a second intensity (I2), said first the beam splitting assembly, wherein the sum of the intensity of and the second intensity (I1+I2) is equal to the intensity of the input beam;
a polarization converter configured to receive one of the first output beam and the second output beam (B1 or B2) output from the beam splitting assembly and convert the polarization thereof;
a polarizing beam splitter (PBS) for receiving the first output beam (B1(I1,P1)) and the polarization converted second output beam (B2(I2,P2)) and dividing them into the polarization beam splitter (PBS) configured to combine to produce a third beam; or the first output beam (B1(I1,P1)) and the second polarization converted output beams (B2(I2, P2)) and splitting them into two output beams after combining them, and providing only one of said two output beams as an input to said coherent beam combining (CBC) system. the coupler configured to
A system characterized by: 29. The system of claim 28, wherein
The beam splitting assembly comprises:
a beam splitter configured to receive an input beam and split the input beam into two beams;
a phase adjuster configured to adjust the phase of one of the two beams;
By receiving the two beams and providing their interference at two interference locations, the first output beam (B1(I1,P1)) and the second output beam (B2(I2,P1) ) and a coupler configured to provide
An electronic controller for monitoring one of said two interference locations and controlling said phase adjuster accordingly to enable constructive or destructive beam interference at the monitored interference location. and the electronic controller configured to provide destructive or constructive beam interference at unmonitored interference locations.
A system characterized by: A hybrid pump module configured to couple to an optical fiber having a core and at least one cladding, comprising:
at least one focusing lens positioned in the optical path of said optical fiber;
a plurality of diode modules arranged in an optical path through the cladding, each configured to output a multimode beam;
at least one core-related module positioned in an optical path by the core,
(a) the ability to output a single-mode beam towards the core;
(b) receiving a beam from said core and coupling the received beam to an output optical fiber;
(c) the ability to receive a beam from said core and reflect the received beam back to said core; and
(d) receiving a beam from said core, reflecting a portion of the received beam back to said core, and coupling another portion of the received beam into an output optical fiber. the core-related module configured to provide
A hybrid pump module characterized by: 31. The hybrid pump module of claim 30, comprising
A module, further comprising a volume Bragg grating (VBG) configured to narrowly lock the wavelength of the beam to a predetermined wavelength range. 31. The hybrid pump module of claim 30, comprising
A hybrid pump module, wherein said plurality of diode modules and said core-associated modules are arranged in at least one row such that their output beams are parallel to each other row by row. 33. The hybrid pump module of claim 32, comprising:
The plurality of diode modules and the core-related modules are arranged in two or more rows,
The hybrid pump module is
at least one polarizer beam combiner positioned in the optical path of the first beam train;
one or more folding mirrors for each additional beam column, each configured to reflect and redirect a corresponding column of parallel beams toward the polarizer beam combiner; further comprising a mirror and
A hybrid pump module characterized by: 31. The hybrid pump module of claim 30, comprising
Each of the diode modules includes:
a broad area laser (BAL);
a folding mirror associated with the broadband laser (BAL), the folding mirror configured to have an optical path between the associated broadband laser (BAL) and the cladding;
optionally, at least one lens disposed between said broadband laser (BAL) and said associated folding mirror and configured to adjust the beam shape of said broadband laser (BAL); include,
A hybrid pump module characterized by: 31. The hybrid pump module of claim 30, comprising
the core related modules include seed related modules;
The seed-related module includes:
at least one seed input configured to couple to a seed laser device;
a folding mirror associated with the seed input in the optical path between the seed input and the core;
optionally, at least one lens disposed between said seed input and said associated folding mirror and configured to adjust the shape of the seed beam;
A hybrid pump module characterized by: 36. The hybrid pump module of claim 35, comprising:
The seed-related module includes:
a beam amplifier configured to amplify the seed beam;
a tap or partial mirror configured to sample the seed beam, and a monitor configured to monitor and alert beam backward transmission;
an isolator configured to allow transmission of light in only one direction;
A hybrid pump module characterized by: 31. The hybrid pump module of claim 30, comprising
the core-related module includes an output module;
The output module is
an output fiber, optionally including an end cap element;
a folding mirror associated with the output fiber in the optical path between the core and the output fiber;
optionally, at least one lens disposed between said output fiber and said associated folding mirror and configured to adjust the shape of the received core beam;
Optimally, including pump dumps and
A hybrid pump module characterized by: 31. The hybrid pump module of claim 30, comprising
the core-related module includes a high reflectance (HR) module;
The high reflectance (HR) module comprises:
a high reflectance (HR) mirror; and
a folding mirror associated with the high reflectance (HR) mirror in the optical path between the core and the high reflectance (HR) mirror;
optionally, at least one lens disposed between said high reflectance (HR) mirror and said associated folding mirror and configured to adjust the shape of its associated beam;
A hybrid pump module characterized by: 39. The hybrid pump module of claim 38, comprising:
The high reflectance (HR) mirror comprises:
further comprising an intracavity adjuster disposed between the high reflectance (HR) mirror and the associated fold mirror and configured to adjust the reflected beam;
A hybrid pump module characterized by: 31. The hybrid pump module of claim 30, comprising
the core-related module includes a partial reflection (PR) module;
The partial reflection (PR) module comprises:
an output fiber, optionally including an end cap;
a partially reflective (PR) mirror positioned in the optical path of the output fiber;
a folding mirror associated with the partially reflective (PR) mirror in an optical path between the core and the partially reflective (PR) mirror;
optionally, at least one lens disposed between said partially reflective (PR) mirror and said associated folding mirror and configured to adjust the shape of its associated beam;
A hybrid pump module characterized by: 31. The hybrid pump module of claim 30, comprising
further comprising at least one heat distribution element selected from the group consisting of a base surface, ribs, threads, and any combination thereof;
A hybrid pump module characterized by: A fiber amplification system,
an optical fiber comprising a core and at least one cladding;
and a hybrid pump module of claim 35 coupled to the first end of the optical fiber.
A system characterized by: 43. The system of claim 42, wherein
A system, further comprising at least one of a pump dump and an end cap element. 43. The system of claim 42, wherein
38. Further comprising a hybrid pump module of claim 37 coupled to a second end of said optical fiber.
A system characterized by: A fiber laser system,
an optical fiber comprising a core and at least one cladding;
39. The hybrid pump module of claim 38 coupled to a first end of said optical fiber;
a fiber Bragg grating (FBG) or the hybrid pump module of claim 40, coupled to the second end of the optical fiber;
A system characterized by: 46. The system of claim 45, wherein
A system, further comprising at least one of a pump dump and an end cap element. A device configured to frequency double optical radiation, comprising:
at least two consecutive nonlinear crystals (NLCs) including a first nonlinear crystal and at least one second nonlinear crystal;
The first nonlinear crystal receives a fundamental beam at a fundamental frequency (FF) and emits a weak second harmonic beam at a second harmonic frequency (FH) together with a strong residual beam at the fundamental frequency (FF). wherein the power ratio between the weak second harmonic beam and the fundamental beam is less than 5×10 ⁻³ to 1;
The at least one second nonlinear crystal comprises the remnant beam at the fundamental frequency (FF) and the second harmonic beam at the second harmonic frequency (FH) from the previous nonlinear crystal (NLC). and output a strong frequency-doubled beam at said second harmonic frequency (FH) together with said remnant beam at said fundamental frequency (FF); the power ratio is greater than 0.3:1;
A device characterized by: 48. The device of claim 47, comprising:
configured to correct the phase relationship between the residual beam at the fundamental frequency (FF) and the second harmonic beam at the second harmonic frequency (FH) prior to being received by the second nonlinear crystal; and at least one phase mismatch compensator (PMC). 49. The apparatus of claim 48, comprising:
at least one configured to sample the intense frequency doubled beam and adjust the phase mismatch compensator (PMC) accordingly to facilitate maximizing the output of the intense frequency doubled beam; A device further comprising two feedback and control systems. 49. The apparatus of claim 48, comprising:
The feedback and control system comprises:
at least one measurement element;
at least one processing element;
and at least one adjustment element configured to adjust the phase mismatch compensator (PMC). 48. The device of claim 47, comprising:
An apparatus, further comprising at least one oven each configured to adjust the temperature of said nonlinear crystal (NLC). 48. The device of claim 47, comprising:
The device, wherein the length (LS) of the first nonlinear crystal is 10% or less of the length (LD) of the second nonlinear crystal (LS≦0.1LD). 53. The apparatus of claim 52, comprising:
the second nonlinear crystal comprises an LBO;
The device, wherein the length (LD) of the second nonlinear crystal is 40 mm or more. 48. The device of claim 47, comprising:
the fundamental frequency (FF) has the properties of infrared (IR) light (λF = 1064 nm),
A device according to claim 1, characterized in that said second harmonic frequency (FH) has the properties of visible light (λH=532 nm). 48. The device of claim 47, comprising:
Each of said nonlinear crystals (NLCs) is configured to have a fundamental beam polarization along its crystal axis or at a 45 degree angle to its crystal axis. A device characterized by: 48. The device of claim 47, comprising:
Each of the nonlinear crystals (NLC) includes at least one material selected from the group consisting of BBO, KTP, LBO, CLBO, DKDP, ADP, KDP, LiIO3, KNbO3, LiNbO3, AgGaS2, and AgGaSe2. device. 48. The device of claim 47, comprising:
The apparatus of claim 1, wherein each lateral dimension of said nonlinear crystal (NLC) is larger than the dimension of the input beam it receives. 48. The device of claim 47, comprising:
An apparatus, further comprising at least one focusing element configured to focus a beam onto said nonlinear crystal (NLC). A method for frequency doubling optical radiation, comprising:
providing a nonlinear crystal (NLC) having a fundamental beam at a fundamental frequency (FF) and a weak second harmonic beam at a second harmonic frequency (FH);
launching by the nonlinear crystal (NLC) an intense frequency-doubled beam at the second harmonic frequency (FH) together with the residual beam at the fundamental frequency (FF);
a power ratio between the weak second harmonic beam and the fundamental beam is less than 5×10 ⁻³ to 1;
A method, wherein the power ratio of said strong frequency-doubled beam to said fundamental beam is greater than 0.3:1. 60. The method of claim 59, wherein
the providing step further includes compensating for a phase mismatch between the fundamental beam and the weak second harmonic beam;
The method is
A method, further comprising controlling a phase mismatch compensator (PMC) to enable maximizing the power of said intense frequency doubled beam. An apparatus configured to frequency-multiply an optical radiation input to provide an output beam at a second harmonic frequency, comprising:
at least two consecutive nonlinear crystals (NLCs), each of said nonlinear crystals comprising a first beam of fundamental frequency (FF) and optionally said first beam from the preceding nonlinear crystal (NLC); the nonlinear configured to receive a second beam at second harmonic frequency (FH) and to emit a strong frequency-doubled beam at said second harmonic frequency (FH) together with a residual beam at said fundamental frequency (FF); a crystal (NLC);
at least one phase mismatch compensator (PMC) disposed between two said nonlinear crystals (NLCs), said fundamental frequency (FF) before being received by said subsequent nonlinear crystals (NLCs); the phase mismatch compensator (PMC) configured to correct a phase relationship between the residual beam and a second harmonic beam at the second harmonic frequency (FH);
A motorized rotation device provided for each of the phase mismatch compensators (PMCs), configured to actively rotate the phase mismatch compensators (PMCs), whereby the residual beam and a motorized rotating device for actively adjusting the correction of the phase relationship with said second harmonic beam. 62. The apparatus of claim 61, comprising:
configured to sample the intense frequency doubled beam and tilt the phase mismatch compensator (PMC) accordingly by the motorized rotating device to allow maximum output of the intense frequency doubled beam. An apparatus, further comprising a feedback and control system. 63. The apparatus of claim 62, comprising:
The feedback and control system comprises:
at least one beam splitter;
at least one measurement element;
at least one processing element;
at least one control element configured to control the motorized rotating device. 62. The apparatus of claim 61, comprising:
the phase mismatch compensator (PMC) comprises an optically transparent window exhibiting chromatic dispersion;
The apparatus of claim 1, wherein the distance required for the beam to pass through the window varies relative to the angle of rotation of the window. 62. The apparatus of claim 61, comprising:
The apparatus of claim 1, wherein the motorized rotating device is configured to rotate the phase mismatch compensator (PMC) in stepped and/or continuous motion. 66. The apparatus of claim 65, comprising:
The apparatus of claim 1, wherein the motorized rotating device is configured to rotate the phase mismatch compensator (PMC) in a dithered fashion bounded by upper and lower limits. 63. The apparatus of claim 62, comprising:
wherein the motorized rotating device is configured to rotate the phase mismatch compensator (PMC) in a dithered fashion bounded by upper and lower limits;
The feedback and control system uses the dither configuration to:
(a) minimizing the subsequent inversion in the nonlinear crystal (NLC), thereby maximizing the power of the output beam;
(b) maximizing the subsequent inversion in the nonlinear crystal (NLC), thereby minimizing the power of the output beam;
(c) adjusting the power of said output beam to a predetermined value between its maximum and minimum values;
An apparatus characterized in that it is configured to provide at least one of: 62. The apparatus of claim 61, comprising:
The motorized rotator rotates the phase mismatch compensator (PMC) in a toggle mode between a maximum harmonic conversion state and a minimum harmonic conversion state to turn the output beam on and off. A device characterized by comprising: 69. The apparatus of claim 68, comprising:
The motorized rotating device is configured to rotate the phase mismatch compensator (PMC) to provide a flat top pulse with controlled rise and fall times and controllable duration. A device characterized by: 62. The apparatus of claim 61, comprising:
The apparatus of claim 1, wherein the motorized rotating device is configured to provide shaped harmonic pulses by rotating the phase mismatch compensator (PMC) according to a lookup table. 62. The apparatus of claim 61, comprising:
The apparatus, further comprising at least one dichroic beam splitter configured to separate at least a portion of said residual beam from said output beam. 62. The apparatus of claim 61, comprising:
The apparatus of claim 1, wherein the power ratio of said strong frequency doubled beam to said first beam at said fundamental frequency is greater than 0.3:1. 62. The apparatus of claim 61, comprising:
An apparatus, further comprising at least one oven each configured to adjust the temperature of said nonlinear crystal (NLC). 74. The apparatus of claim 73, comprising:
configured to actively control the phase mismatch compensator (PMC) to minimize output fluctuations caused by temperature fluctuations of the oven housing the nonlinear crystal (NLC). A device characterized by: 62. The apparatus of claim 61, comprising:
the fundamental frequency (FF) has the properties of infrared (IR) light (λF = 1064 nm),
A device according to claim 1, characterized in that said second harmonic frequency (FH) has the properties of visible light (λH=532 nm). 62. The apparatus of claim 61, comprising:
Each of said nonlinear crystals (NLCs) is configured to have a fundamental beam polarization along its crystal axis or at a 45 degree angle to its crystal axis. A device characterized by: 62. The apparatus of claim 61, comprising:
Each of the nonlinear crystals (NLC) includes at least one material selected from the group consisting of BBO, KTP, LBO, CLBO, DKDP, ADP, KDP, LiIO3, KNbO3, LiNbO3, AgGaS2, and AgGaSe2. device. 62. The apparatus of claim 61, comprising:
The apparatus of claim 1, wherein each lateral dimension of said nonlinear crystal (NLC) is larger than the dimension of the input beam it receives. 62. The apparatus of claim 61, comprising:
An apparatus, further comprising at least one focusing element configured to focus a beam onto said nonlinear crystal (NLC).

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